MECHANICS 

OF  THE 

HOUSEHOLD 


A  COURSE  OF  STUDY  DEVOTED  TO 

DOMESTIC    MACHINERY    AND 

HOUSEHOLD  MECHANICAL 

APPLIANCES 


E.  S.  KEENE 

DEAN   OF   MECHANIC   ARTS 
NORTH   DAKOTA   AGRICULTURAL   COLLEGE 


FIRST  EDITION 


McGRAW-HILL  BOOK  COMPANY,  INC. 
239  WEST  39TH  STREET.    NEW  YORK 


LONDON:  HILL  PUBLISHING  CO.,  LTD. 

G  &  8  BOUVERIE  ST.,  E.  C. 

1918 


COPYRIGHT,  1918,  BY  THE 
McGRAw-HiLL  BOOK  COMPANY,  INC. 


THE  MAPLE  PRESS  YORK  PA 


INTRODUCTION 

This  book  is  intended  to  be  a  presentation  of  the  physical 
principles  and  mechanism  employed  in  the  equipment  that  has 
been  developed  for  domestic  convenience.  Its  aim  is  to  provide 
information  relative  to  the  general  practice  of  domestic  engi- 
neering. The  scope  of  the  work  is  such  as  to  present :  first,  the 
use  of  household  mechanical  appliances;  second,  the  principles 
involved  and  the  mechanism  employed.  It  is  not  exhaustive, 
neither  does  it  touch  many  of  the  secondary  topics  that  might  be 
discussed  in  connection  with  the  various  subjects.  It  does, 
however,  describe  at  least  one  representative  piece  of  each  type 
of  household  apparatus  that  is  used  in  good  practice. 

The  mechanism  used  in  the  equipment  of  a  modern  dwelling 
is  worthy  of  greater  attention,  as  a  course  of  study,  than  it 
has  been  heretofore  accorded.  The  fact  that  any  house,  rural 
or  urban,  may  be  provided  with  all  domestic  conveniences  in- 
cluded in:  furnace  heating,  mechanical  temperature  regulation, 
lighting  facilities,  water  supply,  sewage  disposal  and  other 
appliances,  indicates  the  general  use  of  domestic  machinery  in 
great  variety.  To  comprehend  the  application  and  adapta- 
bility of  this  mechanism  requires  a  knowledge  of  its  general  plan 
of  construction  and  principles  of  operation. 

Heating  systems  in  great  variety  utilize  steam,  hot  water, 
or  hot  air  as  the  vehicle  of  transfer  of  heat  from  the  furnace, 
throughout  the  house.  Each  of  these  is  made  in  the  form  of 
special  heating  plants  that  may  be  adapted,  in  some  special 
advantage  to  the  various  conditions  of  use.  A  knowledge  of 
their  working  principles  and  general  mechanical  arrangement 
furnishes  a  fund  of  information  that  is  of  every  day  application. 

The  systems  available  for  household  water  distribution  take 
advantage  of  natural  laws,  which  aided  by  suitable  mechanical 
devices  and  conveniently  arranged  systems  of  pipes,  provide 
water-supply  plants  to  satisfy  any  condition  of  service.  They 
may  be  of  simple  form,  to  suit  a  cottage,  or  elaborated  to  the 
requirements  of  large  residences  and  made  entirely  automatic  in 

V 

374 i 91 


vi  INTRODUCTORY 

action.  In  each,  the  apparatus  consists  of  parts  that  perform 
definite  functions.  The  parts  may  be  obtained  from  different 
makers  and  assembled  as  a  working  unit  or  the  plant  may  be  pur- 
chased complete  as  some  special  system  of  water  supply.  An  ac- 
quaintance with  domestic  water  supply  apparatus  may  be  of  serv- 
ice in  every  condition  of  life. 

The  type  of  illumination  for  a  house  or  a  group  of  buildings, 
may  be  selected  from  a  variety  of  lighting  systems.  In  rural 
homes,  choice  may  be  made  between  oil  gas,  gasolene,  acetylene 
and  electricity,  each  of  which  is  used  in  a  number  of  successful 
plants  that  differ  only  in  the  mechanism  employed. 

Any  building  arranged  with  toilet,  kitchen  and  laundry  con- 
veniences must  be  provided  with  some  form  of  sewage  disposal. 
Private  disposal  plants  are  made  to  meet  many  conditions  of  serv- 
ice. The  mechanical  construction  and  principles  of  operation 
are  not  difficult  to  comprehend  and  their  adaptation  to  a  given 
service  is  only  an  intelligent  conception  of  the  possible  con- 
ditions of  disposal,  dependent  on  the  natural  surroundings. 

There  are  few  communities  where  household  equipment  can- 
not be  found  to  illustrate  each  of  the  subjects  discussed.  Most 
modern  school  houses  are  equipped  for  automatic  control  of 
temperature,  ventilation  and  humidity.  They  are  further 
provided  with  systems  of  gas,  water  and  electric  distribution 
and  arrangements  for  sewage  disposal.  These  facilities  fur- 
nish demonstration  apparatus  that  are  also  examples  of  their  appli- 
cation. Additional  examples  of  the  various  forms  of  plumbing 
and  pipe  fittings,  valves,  traps  and  water  fixtures  may  be  found 
in  the  shop  of  dealers  in  plumbers  and  steam-fitters  supplies. 

Attention  is  called  to  the  value  of  observing  houses  in  process 
of  construction  and  the  means  employed  for  the  placement  of 
the  pipes  for  the  sewer,  gas,  water,  electric  conduits,  etc.  These 
are  generally  located  by  direction  of  the  specifications  provided 
by  the  architect  but  observation  of  their  installation  is  nec- 
essary for  a  comprehension  of  actual  working  conditions.  It 
is  suggested  that  the  work  be  made  that  of,  first,  acquiring 
an  idea  of  established  practice,  and  second,  that  of  investigating 
the  examples  of  its  application. 


CONTENTS 

PREFACE ' v 

CHAPTER  I 

PAGE 

THE  STEAM  HEATING  PLANT 1 

Heat  of  Vaporization — Steam  Temperature — Gage  Pressure — 
Absolute  Pressure — Two-pipe  System — Separate-return  System — 
Overhead  or  Drop  System — Water-filled  Radiators — Air  Vents — 
Automatic  Air  Vents — Steam  Radiator  Valves — The  House-heat- 
ing Steam  Boiler — Boiler  Trimmings — The  Water  Column — The 
Steam  Gage— The  Safety  Valve— The  Draft  Regulator— Rule  for 
Proportioning  Radiators — Proportioning  the  Size  of  Mains — Forms 
of  Radiators — Radiator  Finishings — Pipe  Coverings — Vapor-sys- 
tem Heating. 

CHAPTER  II 

THE  HOT-WATER  HEATING  PLANT 37 

The  Low-pressure  Hot-water  System — The  High-pressure  Hot- 
water  System — Heating-plant  Design — Overhead  System  of  Hot- 
water  Heating — Expansion  Tanks — Radiator  Connection — Hot- 
water  Radiators — Hot-water  Radiator  Valves — Air  Vents — Auto- 
matic Hot-water  Air  Vents. 

CHAPTER  III 

THE  HOT-AIR  FURNACE 51 

Construction — Furnace-gas  Leaks — Location  of  the  Furnace — 
Flues — Combination  Hot-air  and  Hot-water  Heater. 

CHAPTER  IV 

TEMPERATURE  REGULATION 59 

Hand  Regulation — Damper  Regulator  for  Steam  Boiler — Damper 
Regulators  for  Hot-water  Furnaces — The  Thermostat  Motor — 
Combined  Thermostat  and  Damper  Regulator — Thermostat-motor 
Connections. 

vii 


viii  CONTENTS 

CHAPTER  V 

PAGE 

MANAGEMENT  OF  HEATING  PLANTS ? 70 

General  Advice — The  Economy  of  Good  Draft — General  Firing 
Rules — Weather  and  Time  of  Day — Night  Firing — First-day 
Firing — Other  Day  Firing — Economy  and  Fuels — For  Burning  Soft 
Coal — For  Burning  Coke — Other  Rules  for  Water  Boilers — Air- 
vent  Valves  on  Radiators — The  Air  Valves — End  of  the  Season — 
The  Right  Chimney  Flue — "Smokey"  Chimneys. 

CHAPTER  VI 

PLUMBING 82 

Water  Supply — Water  Cocks — Bibb-cocks — Self-closing  Bibbs — 
Lever-handle  Bibbs — Fuller  Cocks — Wash-tray  Bibbs — Basin 
Cocks — Pantry  Cocks — Sill  Cocks — Valves — Kitchen  and  Laun- 
dry Fixtures — The  Bathroom — Bath  Tubs — Wash  Stands  and 
Lavatories — Traps — Back-venting — Soil  Pipe — Water  Closets — • 
Washout  Closets — Washdown  Closets — Siphon-jet  Closet — Flush 
Tanks — Low-down  Flush  Tank — Opening  Stopped  Pipes — Sewer 
Gas — Range  Boilers — The  Water-back — Excessive  Pressure — 
Blow-off  Cock — Location  of  Range  Boiler — Double  Heater  Con- 
nections— Horizontal  Range  Boilers — Tank  Heaters — Overheater 
Water — Furnace  Hot-water  Heaters — Instantaneous  Heaters. 

CHAPTER  VII 

WATER  SUPPLY 125 

Water  Analysis — Pokegama  Water — River  Water — Artesian  Water 
— Medical  Water — Organic  Matter — Ammonia — Hardness  in 
Water — Iron  in  Water — Water  Softening  With  Hydrated  Silicates 
—Chlorine— Polluted  Water— Pollution  of  Wells— Safe  Distance 
in  the  Location  of  Wells — Surface  Pollution  of  Wells — Water 
Table — The  Divining  Rod — Selection  of  a  Type  of  Well — 
Flowing  Wells — Construction  of  Wells — Dug  Wells — Open  Wells — 
The  Ideal  Well — Coverings  of  Concrete — Artesian  Wells — Driven 
Wells— Bored  Wells— Cleaning  Wells— Gases  in  Wells— Pecu- 
liarities of  Wells — Breathing  Well — Freezing  Wells — Pumps — 
The  Lift  Pump — The  Force  Pump — Tank  Pump — Well  Pumps 
— Wooden  Pump — Pumps  for  Driven  Wells — Deep-well  Pumps 
—Tubular  Well  Cylinders — Chain  Pumps — Rain  Water  Cisterns — 
Filters — The  Hydraulic  Ram — Single-acting  Hydraulic  Ram — 
The  Double-acting  Hydraulic  Ram — Domestic  Water-supply 
Plants — Gravity  Water  Supply — Pressure-tank  System  of  Water 
Supply — The  Pressure  Tank — Power  Water-supply  Plants — 
Electric  Power  Water  Supply— The  Water  Lift. 


CONTENTS  ix 

CHAPTER  VIII 

PAGE 

SEWAGE  DISPOSAL 168 

The  Septic  Tank — The  Septic  Tank  With  a  Sand-bed  Filter— 
The  Septic  Tank  and  Anaerobic  Filter — Limit  of  Efficiency. 

CHAPTER  IX 

COAL 182 

Oxidation  of  Hydrocarbons — Graphitic  Anthracite — Cannel  Coal — 
Lignite  —  Peat  — Wood —  Charcoal  — Coke — Gas-coke — Briquettes 
— Comparative  Value  of  Coal  to  Other  Fuels — Price  of  Coal. 

CHAPTER  X 

ATMOSPHERIC  HUMIDITY 196 

Humidity  of  the  Air — Relative  Humidity — The  Hygrometer — The 
Hygrodeik — Dial  Hygrometers — The  Swiss  Cottage  "Barometer" 
— Dew-point — To  Determine  the  Dew-point — Frost  Prediction — 
Prevention  of  Frost — Humidifying  Apparatus. 

CHAPTER  XI 

VENTILATION 219 

Quantity  of  Air  Discharged  by  a  Flue — Cost  of  Ventilation — The 
Wolpert  Air  Tester — Pneumatic  Temperature  Regulation — 
Mechanical  Ventilation — The  Plenum  Method — Ventilation  Ap- 
paratus— Air  Conditioning — Humidifying  Plants — Vaporization 
as  a  Cooling  Agent — Air-cooling  Plants — Humidity  Control. 

CHAPTER  XII 

GASEOUS  AND  LIQUID  FUELS 250 

Gaseous  and  Liquid  Fuels — Coal  Gas — All-oil  Water  Gas — Pintsch 
|Gas — Blau  Gas — Water  Gas — Measurement  of  Gas — Gas  Meters 
How  to  Read  the  Index — Prepayment  Meters — Gas-service  Rules — 
Gas  Ranges — Lighting  and  Heating  with  Gasoline — Gasoline — 
Kerosene — The  Cold-process  Gas  Machine — The  Hollow-wire  Sys- 
tem of  Gasoline  Lighting  and  Heating — Mantle  Gas  Lamps — 
Open-flame  Gas  Burners — The  Inverted-mantle  Gasoline  Lamp — 
Portable  Gasoline  Lamp — Central  Generator  Plants — Central- 
generator  Gas  Lamps — Boulevard  Lamps — Gasoline  Sad  Irons — 
Alcohol  Sad  Irons — Alcohol  Table  Stoves — Danger  from  Gaseous 
and  Liquid  Fuels — Acetylene-gas  Machine — Types  of  Acetylene 
Generators — Gas  Lighters — Acetylene  Stoves. 


x  CONTENTS 

CHAPTER  XIII 

PAGE 

ELECTRICITY 305 

Incandescent  Electric  Lamps — The  Mazda  Lamp — Candlepower 
— Lamp  Labels — Illumination — The  Foot-candle — The  Lumen — 
Reflectors — Choice  of  Reflector — Lamp  Transformers — Units  of 
Electrical  Measurements — Miniature  Lamps — Effects  of  Voltage 
Variations — Turn-down  Electric  Lamps — The  Dim-a-lite — Gas- 
filled  Lamps — Daylight  Lamps — Miniature  Tungsten  Lamps — 
Flash  Lights — The  Electric  Flat-iron — The  Electric  Toaster — 
Motors,  Fuse  Plugs — Electric  Heaters — Intercommunicating  Tele- 
phones— Electric  Signals — Buzzers — Burglar  Alarms — Annuncia- 
tors— Table  Pushes — Bell-ringing  Transformers — The  Recording 
Wattmeter — To  Read  the  Meter — State  Regulation  of  Meter 
Service — Electric  Batteries — Battery  Formation — Battery  Testers 
— Electric  Conductors — Lamp  Cord — Portable  Cord — Annuncia- 
tor Wire — Private  Electric  Generating  Plants — Storage  Batteries 
—The  Pilot  Cell— National  Electrical  Code— Electric  Light  Wir- 
ing— Outlet  Boxes — Automatic  Door  Switch — Plug  Receptacles 
— Heater  Switch,  Pilot  and  Receptacle — Service  Switch — Local 
Switches — Pilot  Lights — Wall  and  Ceiling  Sockets — Drop  Lights. 

INDEX.  .   385 


MECHANICS  OF  THE  HOUSEHOLD 

CHAPTER  I 
THE  STEAM  HEATING  PLANT, 

The  use  of  steam  as  a  means  of  heating  dwellings  is  common 
in  every  part  of  the  civilized  world.  Plants  of  all  sizes  are  con- 
structed, that  not  only  give  satisfactory  service  but  are  efficient 
in  the  use  of  fuel,  and  require  the  minimum  amount  of  attention. 

The  manufacture  of  steam  heating  apparatus  has  come  to  be 
a  distinct  industry,  and  represents  a  special  branch  of  engineer- 
ing. Many  manufacturing  companies,  pursue  this  line  of  busi- 
ness exclusively.  The  result  has  been  the  development  of  many 
distinctive  features  and  systems  of  steam  heating,  that  are  very 
excellent  for  the  purposes  intended. 

Practice  has  shown  that  large  plants  can  be  operated  more 
economically  than  small  ones.  Steam  may  be  carried  through 
underground,  insulated  pipes  to  great  distances  with  but  small 
loss  of  heat.  This  has  lead  to  the  sale  of  exhaust  steam,  from 
the  engines  of  manufacturing  plants,  for  heating  purposes  and 
the  establishment  of  community  heating  plants,  where  the  dwell- 
ings of  a  neighborhood  are  heated  from  a  central  heating  plant; 
each  subscriber  paying  for  his  heat  according  to  the  number  of 
square  feet  of  radiating  surface  his  house  contains. 

In  the  practice  most  commonly  followed,  with  small  steam 
heating  plants,  the  steam  is  generated  in  a  boiler  located  at  any 
convenient  place,  but  commonly  in  the  basement.  The  steam 
is  distributed  through  insulated  pipes  to  the  rooms,  where  it  gives 
up  its  heat  to  cast-iron  radiators,  and  from  them  it  is  imparted 
to  the  air;  partly  by  radiation  but  most  of  the  heat  is  trans- 
mitted to  the  air  in  direct  contact  with  the  radiator  surface. 

The  heating  capacity  of  a  radiator  is  determined  by  its  out- 
side surface  area,  and  is  commonly  termed,  radiating  surface  or 
heating  surface.  Radiators  of  different  styles  and  sizes  are  listed 
by  manufacturers,  according  to  the  amount  of  heating  surface 

1 


2       MECHANICS  OF  THE  HOUSEHOLD 

each  -possesses.  -Itadiators  are  sold  at  a  definite  amount  per 
square  foot,  and  may  be  made  to  contain  any  amount  of  heating 
surface,  for  different  heights  from  12  to  45  inches. 

The  widespread  use  of  steam  as  a  means  of  heating  buildings 
is  due  to  its  remarkable  heat  content.  When  water  is  converted 
into  vapor  the  change  is  attended  by  the  absorption  of  a  large 
amount  of  heat.  No  matter  at  what  temperature  water  is 
evaporated,  a  definite  quantity  of  heat  is  required  to  merely 
change  the  water  into  vapor  without  changing  its  temperature. 
The  heat  used  to  vaporize  water  in  a  steam  boiler  is  given  up  in 
the  radiators  when  the  steam  is  condensed.  It  is  because  of  this 
property  that  steam  is  such  a  convenient  vehicle  for  transferring 
heat  from  the  furnace — where  it  is  generated — to  the  place  to 
be  warmed.  This  heat  of  vaporization  is  really  the  property 
which  gives  to  steam  its  usefulness  as  a  means  of  heating. 

Heat  of  Vaporization. — The  temperature  of  the  steam  is  com- 
paratively an  unimportant  factor  in  the  amount  of  heat  given 
up  by  the  radiator.  It  is  the  heat  liberated  at  the  time  the  steam 
changes  from  vapor  to  water  that  produces  the  greatest  effect  in 
changing  the  temperature  of  the  house.  QjThis  evolution  of  heat 
by  condensation  is  sometimes  called  the  latent  heat  of  vaporiza- 
tion. It  is  the  heat  that  was  used  up  in  changing  the  water  to 
vapor.  The  following  table  of  the  properties  of  steam  shows  the 
temperatures  and  exact  amounts  of  latent  heat  that  correspond 
to  various  pressures. 

When  water  at  the  boiling  point  is  turned  into  steam  at  the 
same  temperature,  there  are  required  965.7  B.t.u.  for  each  pound 
of  water  changed  into  steam.  In  the  table,  this  is  the  latent 
heat  of  the  vapor  of  water  at  0,  gage  pressure.  As  the  pressure 
and  corresponding  temperature  rise,  the  latent  heat  becomes 
less.  At  10  pounds  gage  pressure,  the  temperature  of  the  steam 
is  practically  240°F.,  but  the  heat  of  vaporization  is  946  thermal 
units.  When  the  steam  is  changed  back  into  water,  as  it  is  when 
condensed  in  the  radiators,  this  latent  heat  becomes  sensible  and 
is  that  which  heats  the  rooms.  The  steam  enters  the  radiators 
and,  coming  into  contact  with  the  relatively  colder  walls,  is  con- 
densed. As  condensation  takes  place,  the  latent  heat  of  the 
steam  becomes  sensible  heat  and  is  absorbed  by  the  radiators 
and  then  transferred  to  the  air  of  the  rooms. 


THE  STEAM  HEATING  PLANT 

PROPERTIES  OF  STEAM 


Absolute  pressure 

Gage  pressure 

Temperature 

Latent  heat 

0 

14.7 

212.00 

965.70 

1 

15.0 

213.04 

964.96 

2 

16.0 

216.33 

962.63 

3 

17.0 

219.45 

960.49 

4 

18.0 

220.40 

958.32 

5 

19.0 

225.25 

958.30 

6 

20.0 

227.95 

954.38 

7 

21.0 

230.60 

952.50 

8 

22.0 

233.10 

950.62 

9 

23.0 

235.49 

949.03 

10 

24.0 

237.81 

947.37 

11 

25.0 

240.07 

945.76 

12 

26.0 

242.24 

944.25 

13 

27.0 

244.32 

942.74 

14 

28.0 

246.35 

941  .  29 

15 

29.0 

248.33 

939.88 

16 

30.0 

250.26 

938.50 

17 

31.0 

252.13 

937.17 

18 

32.0 

253.98 

935.45 

19 

33.0 

255.77 

934.57 

20 

34.0 

257.52 

933.32 

21 

35.0 

259.22 

932.10 

22 

36.0 

260.88 

930.92 

23 

37.0 

262.50 

929.76 

24 

38.0 

264.09 

928.62 

25 

39.0 

265.65 

927.51 

Whenever  water  is  evaporated,  heat  is  used  up  at  a  rate  that 
in  amount  depends  on  its  temperature  and  the  quantity  of  water 
vaporized.  This  heat  of  vaporization  is  important,  not  only  in 
problems  which  relate  to  steam  heating  but  in  all  others  where 
vapor  of  water  exerts  an  influence — ventilation  of  buildings, 
atmospheric  humidity,  the  formation  of  frost,  refrigeration,  and 
many  other  applications  in  practice;  this  factor  is  one  of  the 
important  items  in  quantitative  determinations  of  heat.  It  will 
appear  repeatedly  in  considering  ventilation  and  humidity. 

At  temperatures /'below  the  boiling  point  of  water,  the  heat  of 
vaporization  gradually  increases  until,  at  the  freezing  point, 
it  is  1092  B.t.u.  Water  vaporizes  at  all  temperatures — even 
ice  evaporates — and  the  cooling  effect  produced  by  evapora- 


4  MECHANICS  OF  THE  HOUSEHOLD 

tion  from  sprinkled  streets  in  summer,  or  the  chilling  sensation 
brought  about  by  the  winds  of  winter  are  caused  largely  because 
of  its  effect.  The  evaporation  of  perspiration  from  the  body  is 
one  of  the  means  of  keeping  it  cool.  At  the  temperature  of  the 
body  98.6  the  heat  of  vaporization  is  1046  B.t.u. 

Steam  Temperatures.- — While  the  temperature  of  steam  is  an 
unimportant  factor  in  the  heating  of  buildings  there  are  many 
uses  in  which  it  is  of  the  greatest  consequence.  When  steam  is 
employed  for  cooking  or  baking  it  is  not  the  quantity  of  heat  but 
its  intensity  that  is  necessary  for  the  accomplishment  of  its 
purpose. 

Steam  cookers  must  work  at  a  temperature  suitable  to  the 
articles  under  preparation,  and  the  length  of  time  required  in  the 
process.  Examination  of  the  table  on  page  3,  will  show  that 
steam  at  the  pressure  of  the  air  or  0,  gage  pressure,  has  a 
temperature  of  212°F.,  which  for  boiling  is  sufficiently  intense  for 
ordinary  cooking;  but  for  all  conditions  required  of  steam  cook- 
ing, a  pressure  of  25  pounds  gage  pressure  is  required.  The  tem- 
perature corresponding  to  25  pounds  is  shown  in  the  table  as 
267°F.  Baking  temperatures  for  oven  baking  as  for  bread 
requires  temperatures  of  400°F.  or  higher.  To  bake  by  steam 
at  that  temperature  would  require  a  gage  pressure  of  185  pounds 
to  the  square  inch. 

The  British  thermal  unit  is  the  English  unit  of  measure  of  heat. 
It  is  the  amount  of  heat  required  to  raise  the  temperature  of  a 
pound  of  water  1°F.  From  the  table  it  will  be  seen  that 
steam  at  10  pounds  gage  pressure,  is  only  27.4°  hotter  than 
it  was  at  0  pounds.  In  raising  the  pressure  of  a  pound  of 
steam  from  0  to  10  pounds,  the  steam  gained  only  27.4  B.t.u. 
of  heat.  The  amount  of  heat  gained  by  raising  the  pressure  to 
10  pounds  is  small  as  compared  with  the  heat  it  received  on  vapor- 
izing. The  extra  fuel  used  up  in  raising  the  pressure  is  not  well 
expended.  It  is  customary,  therefore,  in  heating  plants,  to  use 
only  enough  pressure  in  the  boiler  to  carry  the  steam  through 
the  system.  This  amount  is  rarely  more  than  10  pounds  and 
oftener  but  3  or  4  pounds  pressure. 

Gage  Pressure — Absolute  Pressure. — In  the  practice  of  engi- 
neering among  English  speaking  people,  pressures  are  stated  in 
pounds  per  square  inch,  above  the  atmosphere.  This  is  termed 


THE  STEAM  HEATING  PLANT  5 

gage  pressure.  It  is  that  indicated  by  the  gages  of  boilers,  tanks, 
etc.,  subjected  to  internal  pressure.  Under  ordinary  conditions 
the  term  pressure  is  understood  to  mean  gage  pressure,  the  0 
point  being  that  of  the  pressure  of  the  atmosphere.  This  system 
requires  pressures  below  that  of  the  atmosphere  to  be  expressed 
as  a  partial  vacuum,  a  complete  vacuum  being  14.7  pounds  below 
the  normal  atmospheric  pressure. 

In  order  to  measure  positively  all  pressures  above  a  vacuum, 
the  normal  atmosphere  is  14.7  pounds;  all  pressures  above  that 
point  are  continued  on  the  same  scale,  thus: 

Gage  pressure    6  =  14. 7  absolute 

Gage  pressure  10  =  10  +  14.7  =  24.7  absolute 

Gage  pressure  20  =  20  +  14.7  =  34.7  absolute 

Absolute  pressures  are,  therefore,  those  of  the  gage  plus  the 
additional  amount  due  to  the  atmosphere.  All  references  to 
pressure  in  this  work  are  intended  to  indicate  gage  pressure  unless 
specifically  mentioned  as  absolute  pressure. 

Steam  heating  as  applied  to  buildings  may  be  considered  under 
two  general  methods:  the  pressure  system  in  which  steam  under 
pressure  above  the  atmosphere  is  utilized  to  procure  circulation; 
and  the  vacuum  system  in  which  the  steam  is  used  at  a  pressure 
below  that  of  the  atmosphere.  Each  of  these  systems  is  used 
under  a  great  variety  of  conditions,  and  to  some  is  applied  spe- 
cific names  but  the  principle  of  operation  is  very  much  the  same 
in  all  of  a  single  class. 

Steam  heating  plants  are  now  seldom  installed  in  the  average 
home  but  they  are  very  much  employed  in  apartment  houses  and 
the  larger  residences.  In  large  buildings  and  in  groups  of  build- 
ings heated  from  a  central  point,  steam  is  used  for  heating  almost 
exclusively.  The  type  of  plant  employed  for  any  given  condi- 
tion will  depend  on  the  architecture  of  the  buildings  and  their 
surroundings.  In  very  large  buildings  and  in  groups  of  buildings, 
the  vacuum  system  is  very  generally  employed.  This  system 
has,  as  a  special  field  of  heating,  the  elaborate  plants  required  in 
large  units. 

The  low-pressure  gravity  system  of  heating  is  used  in  build- 
ings of  moderate  size,  large  residences,  schools,  churches,  apart- 
ment houses,  and  the  like.  Under  this  form  of  steam  heating  is 


MECHANICS  OF  THE  HOUSEHOLD 


to  be  included  vapor  heating  systems.  This  is  the  same  as  the 
low-pressure  plant  except  that  it  operates  under  pressure  only 
slightly  above  the  atmosphere  and  possesses  features  that  fre- 
quently recommend  its  use  over  any  other  form  of  steam  heating. 
The  term  vapor  heating  is  used  to  distinguish  it  from  the  low- 
pressure  system. 

The  low-pressure  gravity  system,  with  which  we  are  most 
concerned,  takes  its  name  from  the  conditions  under  which  it 

works.  The  low  pressure  re- 
fers to  the  pressure  of  the 
steam  in  the  boiler,  which  is 
generally  3  or  4  pounds;  and 
since  the  water  of  condensation 
flows  back  to  the  boiler  by 
reason  of  gravity,  it  is  a  gravity 
system. 

The  placing  of  the  pipes 
which  are  to  carry  the  steam 
to  the  radiators  and  return  the 
water  of  condensation  to  the 
boiler  may  consist  of  one  or 
both  of  two  standard  arrange- 
-  ments.  They  are  known  as 
the  single-pipe  system  and  the 


two-pipe  system. 

Fig.  1  shows  a  diagram  of  a 
single-pipe  system  in  its  sim- 
plest form.  In  the  figure  the 
pipe  marked  supply  and  return, 
connects  the  boiler  with  the 

radiators.  From  the  vertical  pipe  called  a  riser,  the  steam  is 
taken  to  the  radiators  through  branch  pipes  that  all  slope  toward 
the  riser,  so  that  the  water  of  condensation  may  readily  flow  back 
into  the  boiler.  The  water  of  condensation,  returning  to  the 
boiler,  must  under  this  condition,  flow  in  a  direction  contrary  to 
the  course  of  the  steam  supplying  the  radiators.  In  Fig.  2  is 
given  a  simple  application  of  this  system.  A  single  pipe  from 
the  top  of  the  boiler,  in  the  basement,  marked  supply  and  re- 
turn pipe,  connects  with  one  radiator  on  the  floor  above.  The 


FIG. 


1.  —  Diagram  of  a  gravity  system 
steam  heating  plant. 


THE  STEAM  HEATING  PLANT  7 

radiator  and  all  of  the  connecting  pipes  are  set  to  drain  the 
water  of  condensation  into  the  boiler. 

When  the  valve  is  opened  to  admit  steam  to  the  radiator,  the 
air  vent  must  also  be  opened  to  allow  the  escape  of  the  contained 
air.  The  steam  will  not  diffuse  with  the  air  in  the  radiator  and 
unless  the  air  is  allowed  to  escape,  the  steam  will  not  enter.  As 
the  steam  enters  the  cold  radiator,  it  is  rapidly  condensed, 'and 
collects  on  the  walls  in  the  form  of  dew,  at  the  same  time  giving 
up  its  latent  heat.  The  heat  is  liberated  as  condensation  takes 
place,  and  as  the  dew  forms  on  the  radiator  walls  the  heat  is 

Radiator 


FIG.  2. — A  simple  form  of  steam  heating  plant.     The  furnace  fire  is  controlled 
by  a  thermostat  and  a  damper  regulator. 

conducted  directly  to  the  iron.  The  water  runs  to  the  bottom 
of  the  radiator  and  then  through  the  pipes,  back  to  the  boiler. 
The  water  occupies  but  relatively  a  little  space  and  may  return 
through  the  same  pipe,  while  more  steam  is  entering  the  radiator. 
As  the  steam  condenses  in  the  radiator,  its  reduction  in  volume 
tends  to  reduce  the  pressure  and  thus  aids  additional  steam  from 
the  boiler  to  enter.  In  this  manner  a  constant  supply  of  heat 
enters  the  radiator  in  the  form  of  steam  which  when  condensed 
goes  back  to  the  boiler  at  a  temperature  very  near  the  boiling 
point  to  be  re  vaporized.  It  should  be  kept  in  mind^that  itjs  the 


8 


MECHANICS  OF  THE  HOUSEHOLD 


heat  of  vaporization,  not  the  temperature  of  the  steam  that  is 
utilized  in  the  radiator,  and  that  the  heat  of  vaporization  is  the 
vehicle  of  transfer.  The  water  returning  to  the  boiler  may  be  at 
the  boiling  point  and  the  steam  supplying  the  heat  to  the  radiators 
may  be  at  the  same  temperature. 

Fig.  3  is  a  slightly  different  arrangement  of  the  same  boiler  as 
that  shown  in  Fig.  2,  connected  with  two  radiators  on  different 


adiator 


¥>  Air  Vent 


FIG.  3. — A  gravity  system  steam  heating  plant  of  two  radiators, 
is  governed  by  a  thermostat. 


The  furnace 


floors.     The  same  riser  supplies  both  radiators  with  steam  and 
takes  the  water  of  condensation  back  to  the  boiler. 

Fig.  4  is  an  example  of  the  single-pipe  system  applied  to  a  small 
house.  -  In  the  drawing,  the  boiler  in  the  basement  is  shown 
connected  with  four  radiators  on  the  first  floor  and  three  on  the 
second  floor.  The  pipes  connecting  with  the  more  distant  radia- 
tors are  only  extensions  of  the  pipes  connecting  the  radiators  near 


THE  STEAM  HEATING  PLANT  9 

the  boiler.  As  in  Figs.  1,  2  and  3,  all  of  the  pipes  and  radiators 
are  set  to  drain  back  into  the  boiler.  If  at  any  place  the  pipe  is 
so  graded  that  a  part  of  the  water  is  retained,  poor  circulation 
will  result,  because  of  the  restricted  area  of  the  pipe,  and  the 
radiators  will  not  be  properly  heated.  This  lack  of  drainage  is 
also  a  common  cause  of  hammering  and  pounding  in  steam  sys- 
tems, known  as  water-hammer.  The  formation  of  water-hammer 
is  caused  by  steam  flowing  through  a  water-restricted  area,  into 
a  cold  part  of  the  system,  where  condensation  takes  place  very 


FIG.  4. — The  gravity  system  steam  heating  plant  installed  in  a  dwelling. 

rapidly.  The  condensation  of  the  steam  is  so  rapid  and  complete 
that  the  resulting  vacuum  draws  the  trapped  water  into  the 
space  with  the  force  of  a  hammer  stroke.  The  hammering  will 
continue  so  long  as  the  conditions  exist.  The  pipes  in  the  base- 
ment are  suspended  from  the  floor  joists  by  hangers  as  shown  in 
the  drawing.  In  practice  the  pipes  in  the  basement  are  covered 
with  some  form  of  insulating  material  to  prevent  loss  of  heat. 
As  stated  above,  the  single-pipe  system  may  be  successfully 
used  in  all  house-heating  plants  except  those  of  large  size.  It 


10  MECHANICS  OF  THE  HOUSEHOLD 

requires  the  least  amount  of  pipe  and  labor  for  installation  of  the 
circulating  system  and  when  well  constructed  performs  very 
satisfactorily  all  of  the  functions  required  in  a  small  heating  plant. 

One  of  the  commonest  causes  of  trouble  in  a  single-pipe  system 
is  due  to  the  radiator  connections.  The  single  radiator  connec- 
tion requires  the  entering  steam  and  escaping  water  of  condensa- 
tion to  pass  through  the  same  opening.  Under  ordinary  condi- 
tions this  double  office  of  the  radiator  valve  is  accomplished  with 
satisfaction  but  occasionally  it  is  the  cause  of  considerable  noise. 
At  any  time  the  valve  is  left  only  partly  open  the  steam  will  enter 
and  condense  because  of  the  lower  pressure  inside  the  radiator 
but  the  condensed  water  will  not  be  able  to  escape.  The  water 
has  only  the  force  of  gravity  to  carry  it  out  of  the  radiators  and 
if  it  meets  no  opposition  will  flow  back  through  the  pipe  to  the 
boiler;  but  if  it  is  required  to  pass  a  small  opening  through  which 
steam  is  flowing  in  a  contrary  direction,  the  water  will  be  retained 
in  the  radiators.  Single-pipe  radiators,  therefore,  work  satis- 
factorily only  under  conditions  which  will  permit  the  steam  to 
enter  and  the  water  to  leave  as  fast  as  it  is  formed.  In  ordinary 
use  the  valve  at  any  time  is  apt  to  be  left  slightly  open  and  this 
produces  undesirable  working  conditions. 

In  larger  buildings,  where  greater  distances  require  longer 
runs  of  pipe  and  more  complicated  connections,  and  where  the 
volume  of  condensed  steam  is  too  great  to  be  taken  care  of  in  a 
single  pipe,  this  system  does  not  work  satisfactorily. 

Two-pipe  System. — Fig.  5  is  a  diagram  of  a  two-pipe  system. 
Here,  each  radiator  has  a  supply  pipe,  through  which  the  steam 
enters,  and  a  return  pipe  which  conducts  the  water  away.  The 
branch  pipes  from  a  common  supply  pipe  or  riser,  carry  steam  to 
the  various  radiators  and  all  of  the  return  pipes  empty  into  a  single 
return  pipe  that  takes  the  water  back  to  its  source.  It  will  be 
noticed  that  in  this  case  the  riser  also  connects  at  the  bottom  with 
the  return  pipe.  This  connection  is  made  for  the  purpose  of 
conducting  away  the  condensation  that  takes  place  in  the  con- 
necting pipes.  The  water  will  always  stand  in  these  pipes,  at 
the  same  height  as  the  water  in  the  boiler.  The  supply  pipe  from 
the  boiler,  and  the  branch  pipes  connecting  the  radiators  all  slope 
toward  the  riser.  The  condensation  in  the  connecting  pipes 
does  not  pass  through  the  radiators  as  it  returns  to  the  boiler. 


THE  STEAM  HEATING  PLANT 


11 


An  exception  to  this  general  rule  is  shown  in  the  radiator  on 
the  second  floor.  In  this  case  the  supply  pipe  slopes  down- 
ward as  it  approaches  the  radiator.  To  prevent  carrying  water 
through  the  radiator,  a  small  pipe  under  the  left-hand  valve  con- 
nects with  the  return  pipe  and  the  water  is  thus  conducted  to  the 
main  return  pipe. 

Fig.  6  is  a  simple  application  of  the  arrangement  shown  in 
Fig.  5.  The  steam  may  be  easily  traced  from  the  boiler  to  the 
radiators,  and  back  through 
the  return  pipes  to  its  source. 
The  pipe  marked  R  is  the 
connection  between  the  main 
supply  pipe  and  the  return 
pipe  that  takes  away  the  con- 
densation of  the  riser.  It  is 
connected  to  the  main  return 
pipe  below  the  water  line  of 
the  boiler  and,  therefore,  does 
not  interfere  in  any  way  with 
the  passage  of  the  steam. 
Each  radiator  empties  its 
water  of  condensation  into  a 
common  return  pipe,  that 
finally  connects  with  the  boiler 
below  the  water  line. 

This  arrangement  may  be 
elaborated  to  almost  any  ex- 
tent and  is  an  improvement 
over  the  single-pipe  system. 
It  is  quite  commonly  used  as 
a  method  of  steam  distribu- 
tion, but  it  lacks  the  required 

elements  necessary  to  a  positive  circulation.  As  an  example: 
Suppose  that  the  plant  shown  in  Fig.  6  is  working  and  that 
the  radiator  on  the  first  floor  is  hot,  but  the  valves  of  the 
radiator  on  the  second  floor  are  closed  and  it  is  cold.  The  steam 
entering  at  the  valve  A  of  the  lower  radiator  is  being  condensed 
as  fast  as  the  heat  is  radiated.  The  steam  will  pass  on  through 
the  valve  B  into  the  return  pipe  and  as  soon  as  the  return  pipe 


FIG.  5. — Diagram  showing  the  arrange- 
ment of  a  two-pipe  steam  plant. 


12 


MECHANICS  OF  THE  HOUSEHOLD 


becomes  hot  it  will  contain  steam  at  practically  the  same  pressure 
as  that  in  the  supply  pipe.  This  is  what  takes  place  in  every 
working  steam  plant.  Now  suppose  that  it  is  desired  to  heat 
the  radiator  on  the  floor  above.  The  steam  valve  A  of  the  upper 
radiator  is  opened  to  admit  steam  and  the  return  valve  is  also 
opened  to  allow  the  water  to  escape.  There  is  steam  in  both  the 


Radiator 


Air  Vent 


Ait  Vent 


FIG.  6. — A  two-pipe  steam  heating  plant. 

supply  and  return  pipes  of  the  radiator  below  at  the  same  pres- 
sure, each  tending  to  send  steam  into  the  radiator  above  at  oppo- 
site ends.  This  would  make  a  condition  exactly  the  same  as  a 
single-pipe  system,  with  a  supply  pipe  at  both  ends  of  the  radiator 
and  the  result  would,  of  course,  be  the  same  as  in  the  single-pipe 
system.  There  being  no  place  for  the  water  to  escape  except 
against  the  incoming  steam,  the  water  will  sometimes  surge  back 
and  forth  with  the  customary  noises  peculiar  to  such  conditions. 
It  must  not  be  understood  that  this  will  always  occur,  because 


THE  STEAM  HEATING  PLANT 


13 


systems  of  this  kind  are  in  use  with  fairly  good  results,  but  noisy 
radiators  are  not  at  all  rare  when  working  under  this  condition 
and  the  cause  is  from  that  described.  To  overcome  this  difficulty 
and  change  the  system  into  one  in  which  there  would  be  a  posi- 
tive circulation  from  A  to  B,  in  each  radiator,  allowing  the  steam 
always  to  enter  at  the  valve  A  and  escape  at  B,  the  system  must 
be  changed  to  that  of  separate  returns. 

Separate -return  System. — A  diagram  of  a  separate-return  sys- 
tem is  shown  in  Fig.  7.  In  this  figure,  the  radiator,  boiler  and 
supply  pipes  are  the  same  as 
those  of  Fig.  5,  but  there  is  a 
separate  return  pipe  from 
each  of  the  radiators,  connect- 
ing with  the  main  return  pipe 
at  a  point  below  the  water 
line  of  the  boiler.  Examina-  * 
tion  of  this  diagram  will  show 
that  there  is  an  independent 
circuit  for  the  steam  through 
each  radiator.  The  steam  is 
taken  from  a  common  riser  as 
before  but  after  passing 
through  the  radiator  the 
water  is  returned  by  a  sepa- 
rate pipe  to  the  main  return  _ 
pipe  at  the  bottom  of  the 
boiler.  Fig.  8  is  an  applica- 
tion of  separate-return  system. 
It  is  exactly  the  same  as  Fig. 
6,  except  that  each  radiator 
has  an  independent  return 
pipe.  Steam  must  always 
enter  the  radiators  at  the 

valves  A  and  leave  .at  the  valves  B.  This  makes  a  positive  cir- 
culation that  renders  each  radiator  independent  of  the  others. 
There  is  no  opportunity  for  steam  to  pass  through  one  radiator 
and  interfere  with  the  return  water  of  another;  it,  therefore,  pre- 
vents the  possibility  of  hammering  or  surging  so  eommon  in 
poorly  designed  steam  systems. 


FIG.  7. — Diagram  of  a  separate  return 
steam  system. 


14 


MECHANICS  OF  THE  HOUSEHOLD 


Of  all  the  methods  of  steam  heating  where  the  water  of  con- 
densation is  returned  to  the  boiler  by  reason  of  gravity  this  is 
the  most  satisfactory.  This  plant  requires  a  larger  amount  of 
pipe  than  the  other  systems  described  and  as  a  consequence  the 
cost  of  installation  is  greater  but  it  repays  in  excellence  of 
service  the  extra  expense  incurred. 


Radiator 


Thermostat 


FIG.  8. — A  separate  return  heating  plant. 

Overhead  or  Drop  System. — There  is  yet  another  gravity 
system  of  steam  heating  that  is  sometimes  used  in  large  buildings 
where  economy  in  the  use  of  pipe  is  desired;  this  is  the  overhead 
or  drop  system  shown  in  Fig.  9.  It  is  not  a  common  method  of 
piping  and  is  given  here  only  because  of  its  occasional  use.  In 
the  arrangement  of  the  drop  system,  the  supply  pipe  for  the 
radiators  rises  from  the  boiler  to  the  highest  point  of  the  system 
and  the  branch  pipes  for  the  radiators  are  taken  off  from  the 
descending  pipe.  Its  action  is  the  same  as  that  of  a  single-pipe 


THE  STEAM  HEATING  PLANT 


15 


system  but  the  advantage  gained  by  the  arrangement  is  that  the 
steam  in  the  main  supply  pipes  travels  in  the  same  direction  as 
the  returning  water  of  condensation;  the  cause  of  surging  in  long 
risers  is  thus  eliminated. 

The  two-pipe  systems  of  steam  heating  are  more  certain  in 
action  than  the  single-pipe  methods  because  there  is  nothing  to 
interfere  with  the  progress  of 
the  steam  on  its  way  to  the 
radiators.  In  long  branch 
pipes  of  the  single-pipe  sys- 
tem, the  returning  water  is 
frequently  caught  by  the  ad- 
vancing steam  and  carried  to 
the  end  of  the  pipe,  when 
slugging  and  surging  is  the 
result. 

Water-filled  Radiators.— 
Radiators  frequently  fill  with 
water  and  are  noisy  because 
of  the  position  of  the  valve. 
This  may  be  true  in  any  grav- 
ity system  but  particularly  so  " 
in  radiators  having  a  single 
pipe.  When  the  valve  of  a 
single-pipe  radiator  is  opened 
a  very  small  amount,  the 
entering  steam  is  immedia-  • 


FIG.  9. — Diagram  of  the  overhead  or 
drop  system  steam  plant. 


tely  condensed  but  the  water 
cannot  escape  because  the  in- 
coming steam  entirely  fills  the  opening.  Under  this  condition,  the 
radiator  may  entirely  fill  with  water.  If  the  valve  is  then  opened 
wide,  the  imprisoned  water  has  an  opportunity  to  escape  while 
the  steam  is  entering,  but  the  entering  steam  and  escaping  water 
sets  up  a  water-hammer  that  sometimes  is  terrific  and  lasts 
until  the  water  is  discharged  from  the  radiator.  The  same 
condition  may  exist  in  a  two-pipe  system,  if  the  steam  valve  is 
slightly  opened  while  the  escape  valve  is  closed,  but  in  a  well- 
designed  system  the  radiator  will  be  immediately  emptied  when 
both  valves  are  open. 


16 


MECHANICS  OF  THE  HOUSEHOLD 


Air  Vents. — All  radiators  .must  be  provided  with  air  vents. 
The  vent  is  placed  near  the  top  of  the  last  loop  of  the  radiator, 
at  the  end  opposite  from  the  entering  steam,  as  indicated  in  Figs. 
2,  3,  6,  etc.  The  'object  of  the  vent  is  to  allow  the  air  to 
escape  from  the  radiator  as  the  steam  enters.  Steam  will  not 
diffuse  with  the  air  and,  therefore,  cannot  enter  the  radiator 
until  the  air  is  discharged.  The  air  vent  may  be  a  simple  cock 
such  as  is  shown  in  Fig.  10,  that  must  be  opened  by  hand  when 
the  steam  is  turned  on,  to  allow  the  air  to  escape,  and  closed 
when  the  steam  appears  at  the  vent;  or  it  may  be  an  automatic 
vent,  that  opens  when  the  radiator  cools  and  closes  automatically 
when  the  radiator  is  filled  with  steam.  There  are  many  makes 


FIG.  10.  FIG.  11.  FIG.  12. 

FIG.   10. — A  common  form  of  air  vent  for  radiators. 
FIG.   11. — An  inexpensive  automatic  radiator  air  vent. 
FIG.   12. — Monash  No.  16  automatic  air  vent. 
FIG.   13. — The  Allen  float,  radiator  air  vent. 

of  air  vents  of  both  hand-regulating  and  automatic  types;  of 
the  former,  Fig.  10  furnishes  a  common  example.  The  part 
A,  in  the  figure,  is  threaded  and  screws  tightly  into  a  hole  made 
to  receive  it  in  the  end  loop  of  the  radiator.  The  part  B  is  a 
screw-plug  that  closes  the  passage  Cj  leading  to  the  inside  of  the 
radiator.  When  the  steam  is  turned  on,  the  vent  must  be 
opened  until  the  air  is  discharged,  after  which  it  is  closed  by  the 
hand-wheel  D. 

Automatic  Air  Vents. — These  vents  depend  for  'their  action  on 
the  expansion  of  a  part  of  the  valve  due  to  the  temperature  of  the 
steam.  The  valve  remains  closed  when  hot  and  opens  when 
cold.  The  difference  in  temperature  between  the  steam  and  the 
expelled  air  from  the  radiator  is  the  controlling  factor.  In  the 


THE  STEAM  HEATING  PLANT  17 

automatic  vent  shown  in  Fig.  11,  the  part  A  is  screwed  into  the 
radiator  loop.  The  discharge  C  is  open  to  the  air  or  connected 
with  a  drip  pipe,  which  returns  the  water  to  the  basement.  The 
cylinder  D,  which  closes  the  passage  B,  is  made  of  a  material  of  a 
high  coefficient  of  expansion.  The  piece  Z>,  when  cool,  is  con- 
tracted sufficiently  to  leave  the  passage  B  open  to  the  air.  When 
the  steam  is  turned  on,  the  expelled  air  from  the  radiator  escapes 
through  B  and  C,  but  when  the  steam  reaches  D  the  heat  quickly 
expands  the  piece  and  closes  the  vent. 

Most  automatic  vents  require  adjusting  when  put  in  place  and 
occasionally  need  readjustment.  The  cap  0,  of  Fig.  11,  may  be 
removed  with  a  wrench  and  a  screw-driver  used  to  adjust  the 
piece  Z>,  so  as  to  shut  off  the  steam  when  the  radiator  is  filled 
with  steam.  The  expanding  piece  is  simply  screwed  down  until 
the  steam  ceases  to  escape. 

Fig.  12  is  another  style  of  automatic  vent,  constructed  on  the 
same  principle  as  that  of  Fig.  11,  but  probably  more  positive  in 
action.  In  this  vent  the  part  A  attaches  to  the  radiator.  The 
expanding  portion  B  is  made  in  the  form  of  a  hollow  cylinder, 
through  which  the  air  and  steam  escape  to  the  atmosphere.  It 
is  longer  than  the  corresponding  piece  in  the  other  vent  and  is 
more  sensitive  because  of  its  greater  length  and  exposed  surface. 
As  the  piece  B  elongates  from  expansion,  the  upper  end  makes  a 
joint  with  the  conical  piece  D.  The  shape  of  this  latter  piece 
gives  better  opportunity  for  a  tight  joint  than  in  the  other  form 
of  vent  and  in  practice  gives  better  service. 

Fig.  13  is  a  cross-section  of  the  Allen  vent.  This  is  an  example 
of  a  vent  which  depends  for  its  action  on  a  float.  Whenever 
sufficient  water  accumulates  in  the  body  of  the  vent  to  raise 
the  float,  it  closes  the  vent  by  means  of  its  buoyancy.  The  body 
of  the  vent  shown  in  Fig.  13  is  composed  of  two  concentric  cylin- 
ders. The  float  E  occupies  the  inner  cylinder,  while  surrounding 
it  is  the  outer  cylinder  D.  The  outer  cylinder  is  entirely  closed 
except  a  little  hole  at  G.  The  float  is  made-  of  light  metal  and 
fits  loosely  in  the  inner  cylinder.  The  steam  from  the  radiator 
condenses  in  the  vent  until  the  inner  cylinder  is  filled  with  water, 
up  to  the  opening  A.  The  float  by  its  buoyancy  keeps  the  open- 
ing in  B  stopped,  and  no  steam  can  escape.  The  air  of  the  outer 
cylinder  D  is  expanded  by  the  heat  of  the  steam  and  most  of  the 


18 


MECHANICS  OF  THE  HOUSEHOLD 


air  escapes  through  the  hole  G.  When  the  radiator  cools,  the 
rarefied  air  in  D  contracts  and  draws  the  water  from  the  inner 
cylinder  into  the  space  D;  this  allows  the  float  to  fall  and  unstop 
the  opening  in  B.  When  the  steam  again  reaches  the  vent,  the 
heat  expands  the  air  in  D  and  forces  the  water  into  the  inner 
cylinder;  the  float  is  again  raised  and  stops  the  opening  in  B. 

Many  other  air  vents  are  in  common  use  but  most  of  them 
operate  on  one  or  the  other  of  the  principles  described.  Fig.  11 
is  a  relatively  inexpensive  vent,  while  Fig.  12  is  higher-priced. 

Steam  Radiator  Valves. — Like  most  other  mechanical  appli- 
ances that  are  extensively  used,  radiator  valves  are  made  by  a 
great  number  of  manufacturers  and  in  many  different  forms. 


FIG.  14. — Steam  radiator 
valve. 


FIG.   15. — Sectional  view  of  a 
steam  radiator  valve. 


Some  possess  special  features  that  are  intended  to  increase  their 
working  efficiency  but  the  type  of  radiator  valve  most  commonly 
used  for  ordinary  construction  -is  that  illustrated  in  Figs.  14  and 
15.  It  is  a  style  of  angle  valve  that  takes  the  place  of  an  elbow 
and  being  made  with  a  union  joint,  also  furnishes  a  means  of 
disconnecting  the  radiator  without  disturbing  the  pipes.  Fig. 
14  is  an  outside  view  of  the  valve  and  Fig.  15  shows  its  mechan- 
ical construction.  The  part  B  screws  onto  the  end  of  the  steam 
pipe  and  A  connects  with  the  radiator.  The  part  C-D  is  the 
union.  The  nut  C  screws  onto  the  valve  and  makes  a  steam- 


THE  STEAM  HEATING  PLANT  19 

tight  joint  at  D,  between  the  parts.  In  case  it  is  desired  to 
remove  the  radiator,  it  furnishes  an  easy  means  of  detaching  the 
valve.  The  composition  valve-disc  E  makes  a  seat  on  the  brass 
ring  directly  under  it,  to  shut  off  the  steam.  In  case  the  valve 
leaks,  the  disc  may  be  removed  by  taking  the  valve  casing  apart 
at  G.  The  worn  disc  can  then  be  replaced  with  a  new  one  which 
may  be  obtained  from  the  dealer  who  furnished  the  valve.  The 
only  moving  part  of  the  valve  exposed  to  the  air  is  at  the  point 
where  the  valve-stem  S  enters  the  casing.  The  joint  is  made 
steam-tight  by  the  packing  P.  The  packing  is  greased  candle 
wicking  that  is  wound  around  the  stem  and  held  tightly  in  place 
by  the  screw-cap  H.  If  the  valve  leaks  at  this  joint,  a  turn  or 
two  with  a  wrench  will  stop  the  escape  of  the  steam. 

THE  HOUSE-HEATING  STEAM  BOILER 

House-heating  boilers  were  formerly  made  of  sheet  metal  and 
are  still  so  constructed  to  some  extent,  but  by  far  the  greater 
number  are  now  made  of  cast  iron.  Sheet-metal  boilers  are 
constructed  at  the  factory,  ready  to  be  installed,  but  the  cast-iron 
type  is  made  in  sections  and  assembled  to  make  a  complete 
boiler,  at  the  time  the  plant  is  erected.  Sectional  boilers  are 
convenient  to  install,  on  account  of  the  possibility  of  handling 
the  parts  in  a  limited  space,  that  would  not  admit  an  assembled 
boiler  without  tearing  down  a  part  of  the  basement  for  admission. 

Cast-iron  boilers  as  commonly  used  for  heating  dwellings  are 
made  in  two  definite  styles.  The  small  sizes  are  cylindrical  in 
form  and  are  used  for  either  steam  or  hot-water  heating.  The 
larger  sizes  are  made  as  illustrated  in  Figs.  16  and  17,  the 
former  being  an  outside  view,  and  the  latter  showing  the  internal 
arrangement  of  the  same  boiler.  The  fire-box,  water  space  and 
smoke  passages  are  easily  recognized.  Each  division  represents 
a  separate  section  which  assembled  as  that  in  the  figures  makes  a 
complete  boiler  with  a  common  opening  as  shown  at  the  top  of 
Fig.  17.  These  boilers  are  used  for  residences  of  large  size  and 
for  buildings  of  less  than  10,000  feet  of  radiating  surface.  For 
large  buildings,  the  steam  is  most  commonly  generated  in  boilers 
built  for  high  pressure. 

In  small  plants,  intended  for  either  steam  or  hot-water  heating, 


20  MECHANICS  OF  THE  HOUSEHOLD 

the  cylindrical  style  of  boiler  shown  in  Fig.  18  is  commonly  used. 
As  constructed  by  different  manufacturers,  the  parts  differ  quite 
materially  but  Fig.  18  shows  all  of  the  essential  features  and 
serves  to  illustrate  the  different  working  parts.  The  sections 
into  which  the  boiler  is  divided  are  indicated  on  the  left-hand 
side  of  the  figure  by  the  numbers  1  to  6.  The  parts  from  1  to  5 
are  screwed  together  with  threaded  nipples,  joining  the  central 
column.  The  part  6  contains  the  grate  and  the  ash-pit,  with 
the  draft  and  clean-out  doors. 


FIG.  16.  FIG.  17. 

FIG.   16. — Sectional  cast-iron  boiler  for  steam  or  hot-water  heating. 
FIG.   17 — Interior  view  of  the  boiler  shown  in  Fig.  16. 

The  drawing  shows  the  boiler  cut  through  the  middle  length- 
wise and  exposes  to  view  all  of  the  essential  features.  The  fire- 
box and  the  spaces  occupied  by  the  steam  and  water  are  easily 
recognized.  It  will  be  seen  that  the  water  space  surrounds  the 
fire-box  except  at  the  bottom  and  that  the  space  above  the  fire- 
box presents  a  large  amount  of  heating  surface  to  the  flame  and 
heated  gases  as  they  pass  to  the  chimney.  The  arrows  show 
their  course;  first  through  the  openings  near  the  center,  then 
through  those  further  away.  The  object  being  to  keep  the 


THE  STEAM  HEATING  PLANT 


21 


heat  as  long  as  possible  in  contact  with   the  heating  surfaces 
without  interfering  with  the  draft. 

There  is  no  standard  method  of  rating  the  heating  capacity  of 
boilers  of  this  kind  and  as  a  consequence,  boilers  of  different 
makes — for  the  same  rating — are  not  the  same  in  actual  heating 
capacity.  The  boilers  are  sold  by  their  makers  in  sizes  that 


w 


FIG.   18. — Sectional  view  of  the  cylindrical  type  of  cast-iron,  sectional  boiler. 

are  intended  to  furnish  heat  sufficient  to  supply  a  definite  num- 
ber of  square  feet  of  radiating  surface.  The  ratings  are  quite 
generally  too  high  for  the  weather  conditions  of  the  Northwest. 
A  common  practice  with  contractors  is  to  select  boilers  for  a 
given  plant  50  per  cent,  and  even  100  per  cent,  larger  than  those 
rated  by  the  manufacturers  for  the  same  amount  of  radiation. 


22 


MECHANICS  OF  THE  HOUSEHOLD 


Some  manufacturers  sell  their  boilers  at  honest  ratings  but  they 
are  exceptions. 

In  specifying  the  capacity  of  a  house-heating  plant  it  is  common 
practice  to  require  the  boiler  to  be  of  such  size  as  will  easily 
heat  a  definite  number  of  square  feet  of  radiating  surface.  The 
radiators  are  required  to  possess  sufficient  radiating  surface  to 
keep  the  house  at  70°F.  in  any  weather.  In  the  absence  of  any 
rules  or  specifications  for  determining  the  heating  capacity  of  the 
boiler,  the  only  means  of  securing  a  satisfactory  plant  is  to  require 
a  guarantee  of  the  contractor  to  install  a 
boiler  such  as  will  fulfil  the  conditions  stated 
above. 

Boiler  Trimmings. — Attached  to  the 
boiler  and  required  for  its  safe  operation  are 
a  number  of  appliances  that  demand  special 
attention.  The  office  of  each  part  should  be 
thoroughly  appreciated  and  the  mechanical 
construction  should  be  fully  understood. 
An  intimate  acquaintance  with  the  details  of 
the  plant,  helps  to  make  its  operation  satis- 
factory and  adds  to  the  efficiency  with  which 
it  can  be  made  to  perform  its  duty. 

The  Water  Column.— In  Fig.  18  the 
water  column  is  shown  at  C.  It  is  attached 
to  the  'boiler  by  pipes  at  points  above  and 
below  the  water  line,  so  as  to  allow  a  free 
passage  of  the  water  of  the  boiler  to  the  in- 
terior. The  water  line  should  be  3  or  4  inches  above  the  top 
heating  surface.  Attached  to  the  water  column  is  the  gage-glass, 
the  try-cocks  T  and  T  and  the  steam  gage  G. 

The  object  of  the  gage-glass  is  to  show  the  height  of  the  water 
in  the  boiler.  It  is  shown  in  place  on  the  boiler  in  Figs.  16  and 
18  and  in  detail  in  Fig.  19.  The  lower  part  of  the  gage-glass 
occupies  a  position  on  the  boiler  about  2  inches  above  the  top 
heating  surface.  When  the  boiler  is  working,  the  level  of  the 
water  should  always  be  visible  in  the  glass  and  should  stand 
normally  one-third  to  one-half  full. 

The  water  gage  is  attached  to  the  water  column  by  two  brass 
valves  V.  The  valves  are  provided  so  that  in  case  the  water 


FIG. 


19.— The    water 
gage. 


THE  STEAM  HEATING  PLANT  23 

glass  should  be  broken  the  openings  may  be-  closed.  The  ends 
of  the  glass  are  made  tight  by  "stuffing-boxes"  marked  C,  in  the 
figure.  The  packing  S  is  generally  in  the  form  of  rubber  rings 
but  greased  wicking  may  be  used  if  necessary  as  in  the  case  of 
valve-stems. 

The  try-cocks  T  and  T  (Fig.  18)  are  also  intended  to  indicate  the 
approximate  height  of  the  water  in  the  boiler  and  should  the  water 
glass  be  broken  may  be  used  in  its  place.  The  openings  of  the  try- 
cocks  point  toward  the  floor.  When  a  cock  is  opened,  should 
steam  alone  escape,  it  will  be  absorbed  by  the  air,  but  if  water  is 
escaping,  although  much  of  it  will  be  vaporized  and  look  like 
steam,  some  of  the  water  will  be  carried  to  the  floor  and  produce 
a  wet  spot.  When  the  cock  is  opened  wide  the  escaping  water 
from  the  lower  cock  should  always  wet  the  floor. 

The  drip-cock  P  (Fig.  18)  at  the  bottom  of  the  gage-glass  is 
for  draining  the  water  column  and  for  blowing  out  any  deposit/ 
that  may  collect  in  the  opening  of  the  column.  This  cock  should 
be  opened  occasionally  to  assure  the  correctness  of  the  gage-glass. 

The  Steam  Gage. — Steam  pressure  is  measured  in  pounds  to 
the  square  inch  above  the  pressure  of  the  atmosphere.  The 
gages  used  for  indicating  the  pressure  of 
the  steam  are  made  in  several  forms  but 
the  type  most  commonly  used  is  that 
shown  in  Fig.  20.  It  is  known  as  the 
Bourdon  type  of  gage  and  takes  its  name 
from  the  bent  tube  A}  which  furnishes  its 
active  principle.  The  Bourdon  barometer 
invented  in  1849  employed  this  form  of 
sensitive  tube.  In  the  drawing  the  face  s 

of  the  gage  has  been  removed  to  show  FIG.  20.— Typical  Bour- 
the  working  parts.  The  sensitive  part  is 
the  flat  elastic  tube  A,  which  is  bent  in 
the  form  of  a  circle.  When  the  pressure  of  the  steam  enters  at 
S  the  air  in  the  tube  is  compressed  and  the  tube  tends  to  straighten. 
The  movement  of  the  tube  caused  by  the  steam  pressure  is  com- 
municated to  the  pointer  by  a  link  connection  and  gear  as  shown 
in  the  drawing.  The  amount  of  straightening  of  the  tube  will 
be  in  proportion  to  the  steam  pressure  and  is  indicated  by^the 
numbers  marked  on  the  face  of  the  gage.  When  the  pressure  is 


24 


MECHANICS  OF  THE  HOUSEHOLD 


released,  the  tube  returns  to  its  original  position  and  the  spiral 
spring  C  turns  the  hand  back  to  its  first  position. 

The  Safety  Valve. — All  steam  boilers  should  be  provided 
with  safety  valves  as  a  safeguard  against  excessive  steam  pres- 
sures. Of  the  various  types  of  safety  valves,  that  known  as  the 
pop-valve  is  most  commonly  used  on  house-heating  boilers.  It 
is  indicated  at  W  in  Fig.  18  and  is  shown  in  section  in  Fig.  21. 
The  part  A  is  screwed  into  the  top  of  the  boiler  at  any  convenient 
place.  The  pressure  of  the  spring  C  holds  the  valve  B  on  its  seat 
until  the  internal  pressure  reaches  a  certain  in- 
tensity at  which  the  valve  is  set,  when  it  opens 
and  allows  the  excess  steam  to  escape.  When 
the  pressure  is  reduced,  the  spring  forces  the 
valve  back  on  its  seat.  The  handle  D  permits 
the  valve  to  be  lifted  at  'any  time  as  an  assur- 
ance that  it  is  in  working  order.  This  should 
be  done  occasionally,  as  the  valve  may  stick  to 
the  seat  after  long  standing  and  allow  the  pres- 
sure to  rise  above  the  point  at  which  it  should 
"pop." 

The  valve  may  be  set  to  "blow  off"  at  any  de- 
sired pressure  by  the  adjusting  piece  E.  House- 
heating  boilers  generally  have  their  safety  valves 
set  to  blow  off  at  8  or  10  pounds. 

The  Draft  Regulator. — As  a  means  of  auto- 
matic control  of  the  steam  pressure,  the  draft  regulator  is  fre- 
quently used  to  so  govern  the  fire  that  when  a  certain  steam 
pressure  is  reached,  the  direct  draft  will  be  automatically  closed 
and  the  check-draft  damper  opened.  The  draft  regulator  is 
shown  in  place  at  D  in  Fig.  18,  and  will  also  be  found  in  Fig.  16. 
A  detailed  description  of  the  regulator  will  be  found  on  pages 
60  and  61. 


FIG.  21. — Cross- 
section  of  a  pop 
valve. 


RULE  FOR  PROPORTIONING  RADIATORS 

Rules  for  determining  the  amount  of  radiating  surface  that 
will  be  required  to  satisfactorily  heat  a  building  to  70°F.  regar$- 
less  of  weather  conditions  are  entirely  empirical,  that  is,  they  are 
derived  from  experience.  It  is  evident  that  no  definite  rule  can 


THE  STEAM  HEATING  PLANT  25 

be  established  that  will  take  into  account  the  method  of  building 
construction,  the  kind  and  amount  of  materials  that  make  up 
the  walls  and  the  quality  of  workmanship  employed.  These 
variable  quantities  coupled  with  the  changing  climatic  conditions 
of  temperature  and  wind  velocity  produce  a  complication  that 
cannot  be  overcome  in  a  formula  that  will  give  exact  results. 

Many  rules  are  in  use  for'this^frtlrpose,  no  two  of  which  give 
exactly  the  same  results  when  applied  to  a  problem.  A  common 
practice  is  to  apply  one  of  the  rules  in  use  and  then  under 
conditions  of  exceptional  exposure,  to  add  to  the  amount  thus 
calculated  as  experience  may  dictate.  ^.^ 

The  following  rule  by  Professor  R.  G.  Carpenter  of  Cornell 
University  was  taken  from  a  handbook  publishea  by  the  J.  L. 
Mott  Iron  Works  of  New  York.  This  company  manufactures 
and  deals  in  all  kinds  of  apparatus  entering  into  steam  and  hot- 
water  heating  and  the  rule  is  given  as  one  that  has  produced 
satisfactory  results. 

RULE.  —  Add  the  area  of  the  glass  surface  in  the  room  to  one-quarter 
of  the  exposed_  wall  surface,  and  to  this  add  from  one-fifty-fifth  to 
three-fifty-fifths  of  the  cubical  contents  (one-fifty-fifth  for  rooms  on 
upper  floor,  two-fifty-fifths  for  rooms  on  first  floor  and  three-fifty-fifths 
for  large  halls);  then  for  steam  multiply  by  0.25,  and  for  hot  water 
byO.40. 

Example.  —  A  room  20  by  12  by  10  feet  with  glass  exposure  of  48 
feet,  y±  of  wall  exposure  (two  sides  exposed)  320  feet  =  80,  >£5  of 
2400  =  44. 

48  +  80  +  44  =  172  X  0.25  =  43  feet. 
If  you  add  £55  the  surface  would  be  54  feet. 
If  you  add  %5  the  surface  would  be  65  feet. 

PROPORTIONING  THE  SIZE  OF  MAINS 

For  any  size  system  of  steam  or  water  heating  the  following 
rule  will  be  found  entirely  satisfactory  for  mains  100  feet  long; 
for  each  100  feet  additional  use  a  size  larger  ratio. 

RULE.  — 

« 


d  r 

r  represents  ratio  of  main  in  inches  for  each  100  feet  of  surface;  d, 
diameter  of  pipe;  R,  quantity  of  radiation  carried  by  size  of  pipe;  a, 
area  of  pipe  in  inches. 


26  MECHANICS  OF  THE  HOUSEHOLD 

From  this  the  following  table  has  been  constructed: 


'Diameter  of  pipe 

Area  of  pipe 

Ratio  to  each  100 
feet  of  surface 

Quantity  of  radia- 
tion, steam  or 
water,  on  a 
given  size  pipe 

IH 

1.767 

2.10 

84 

2 

3.141 

1.57 

200 

2^ 

4.908 

1.25 

400 

3 

7.069 

1.04 

700 

3M 

9.621 

0.90 

1,062 

4 

12.566 

0.78 

1,590 

4K 

15.904 

0.70 

2,272 

5 

19.625 

0.63 

3,120 

6 

28.274 

0.52 

5,440 

7 

38.484 

0.45 

8,550 

8 

50.265 

0.40 

12,556 

9 

63.617 

0.35 

18,100 

10 

78.540 

0.30 

25,300 

FORMS  OF  RADIATORS 

Radiators  are  much  the  same  in  appearance  for  both  steam  and 
hot-water  heating.  They  are  hollow  cast-iron  columns  so  de- 
signed that  they  may  be, fastened  together  in  units  of  any  number 
of  sections.  The  sections  are  made  in  size  to  present  a  definite 
number  of  square  feet  of  outside  surface  that  is  spoken  of  as 
radiating  surface.  The  amount  of  radiating  surface  in  any 
radiator  depends  on  its  height  and  the  contour  of  the  cross-sec- 
tion. The  radiator  sections  may  be  made  in  the  form  of  a  single 
column  as  Fig.  22  or  they  may  be  divided  into  two,  three,  four  or 
more  columns  to  increase  their  radiating  surface. 

The  following  table,  taken  from  a  manufacturer's  catalogue, 
shows  the  method  of  rating  the  heating  capacity  of  a  particular 
design.  In  the  table,  the  first  column  gives  the  number  of  sec- 
tions in  the  radiator,  the  second  column  states  the  length  of  the 
radiator  in  inches.  The  columns  headed  heating  surface  give 
the  heights  of  the  sections  in  inches  and  the  amount  of  radiating 
surface  in  various  radiators  of  different  heights  and  numbers  of 
sections.  As  an  example:  This  table  refers  to  the  three-column 
radiators  of  Fig.  23.  Such  a  radiator  32  inches  high  with  10 


THE  STEAM  HEATING  PLANT 


27 


sections  would  contain  45  square  feet  of  radiating  surface  and 
would  be  25  inches  in  length. 


No.  of  sections 

Length  2H  in.  per 
section 

Heating  surface  —  square  feet 

ll 

*t 

U5CO 

6 

,oa 

.5  t 

00  «5 

co 

f* 

I 

I 

i'i 

I 

js 

p 

2 

5 

12 

10 

9 

7M 

Qy2 

5K 

3 

7% 

18 

15 

13^2 

11/4 

9% 

8M 

4 

10 

24 

20 

18 

15 

13 

11  < 

5 

12K 

30 

25 

22^ 

18% 

16^ 

13% 

6 

15 

36 

30 

27 

22^ 

19K 

16^x^ 

7 

17K 

42 

35 

31^ 

26M 

22% 

1  OL/ 

8 

20 

48 

40 

36 

30 

26 

22 

9 

22  K 

54 

45 

40>£ 

33% 

29^ 

24% 

10 

25 

60 

50 

45 

37^ 

32^ 

27^ 

11 

271^ 

66 

55 

49K 

41M 

35% 

30^ 

12 

30 

72 

60 

54 

45 

39 

33 

13 

32K 

78 

65 

58K 

48% 

42K 

35% 

14 

35 

84 

70 

63 

52K 

45^ 

3S^2 

15 

37^2 

90 

75 

67^ 

56^ 

48% 

41  M 

16 

40 

96 

80 

72 

60 

52 

44. 

17 

42^ 

102 

85 

76H 

63% 

55M 

46% 

18 

45 

108 

90 

81 

67^ 

58^ 

49^ 

19 

47>^ 

114 

95 

85  % 

71K 

61% 

52K 

20 

50 

120 

100 

90 

75 

65 

55 

21 

52^ 

126 

105 

94  % 

78% 

68^ 

57% 

22 

55 

132 

110 

99 

821^ 

71^ 

6Qi^ 

23 

57^ 

138 

115 

103^ 

86H 

74% 

6314 

24 

60 

144 

120 

108 

90 

78 

66 

25 

62^ 

150 

125 

H2M 

93% 

&1K 

68% 

26 

65 

156 

130 

117 

97^ 

84^ 

713^ 

27 

67^ 

162 

135 

121  -Hi 

ioiM 

87% 

74K 

28 

70 

168 

140 

126 

105 

91 

77 

29 

72^ 

174 

145 

130^ 

108% 

94K 

79% 

30 

75 

180 

150 

135 

H2K 

97K 

82^ 

31 

77^ 

186 

155 

139^ 

H6M 

100% 

85M 

32 

80 

192 

160 

140 

120     104 

88 

Fig.  22  is  a  radiator  made  up  of  eight  single-column  sections. 


28 


MECHANICS  OF  THE  HOUSEHOLD 


In  Fig.  23  is  shown  five  three-column   radiators,  varying  in 
height  from  20  to  45  inches. 

The  sections  of  steam  radiators  are  joined  together  at  the  bot- 
tom with  close-nipples,  so  as  to  leave  an  opening  from  end  to 
end.  The  sections  of  hot-water  radiators  are  joined  in  the  same 
manner,  except  that  there  is  an  opening  at  both  top  and  bottom. 
Fig.  30  shows  the  openings  of  a  hot-water  radiator  installed  as 
direct-indirect  heater.  Fig.  24  illustrates  a  special  form  of 
radiator  that  is  intended  to  be  placed  under  windows  and  in 
other  places  that  will  not  admit  the  high 
form.  Such  a  radiator  as  that  shown 
in  the  picture  is  often  covered  with  a 
window  seat  and  in  cold  weather  becomes 
the  favorite  place  of  the  sitting  room. 
Another  special  form  is  that  of  Fig.  25. 


FIG.  22.  FIG.  23. 

FIG.  22. — Single  column  steam  radiator. 

FIG.  23. — Three-column  radiators  of  different  heights;  for  steam  or  hot-water 
heating. 

As  a  corner  radiator  this  style  is  much  to  be  preferred  to  the 
ordinary  method  of  connection;  here  the  angle  is  completely 
filled — there  is  no  open  space  in  the  corner. 

Wall  radiators  such  as  shown  in  Fig.  2§  are  made  to  set 
close  to  the  wall,  where  floor  space  is  limited.  They  are  par- 
ticularly adapted  for  use^ui--n«rrew4ialls,  bathrooms  and  other 
places  whefe  the-Drdlnary  type  could  not  be  conveniently  used. 

A  radiator  that  will  appeal  to  all  neat  housekeepers  is  that  of 
Fig.  27.  It  does  not  stand  on  the  floor  as  in  the  case  of  the 


THE  STEAM  HEATING  PLANT 


29 


ordinary  type,  but  is  hung  from  the  wall  by  concealed  brackets. 
The  difficulty  of  sweeping  under  this  radiator  is  entirely  avoided. 
Fig.  28  is  a  radiator  designed  to  furnish  a  warming  oven  for 
plates  and  for  heating  the  room  at  the  same  time.  It  is  some- 
times installed  in  dining  rooms. 


FIG.  24. — Six-column,    low   form   of   hot-water   radiators   to   be   placed   under 

windows. 

The  ordinary  method  of  heating  by  the  use  of  radiators  is 
known  as  the  direct  method.  The  air  is  heated  by  coming 
directly  into  contact  with  the  radiators  and  distributed  through 


FIG.  25. — Two-column  corner 
radiator  for  steam  heating. 


FIG.  26. — Wall  form,  radiator  for  steam 
or  hot  water. 


the  room  by  convection.  If  the  arrangement  is  such  that  the 
air  is  brought  from  outdoors  and  heated  by  the  radiator  before 
entering  the  room,  it  is  called  the  indirect  method  of  heating. 
Such  an  arrangement  is  illustrated  in  Fig.  29.  The  radiator 


30  MECHANICS  OF  THE  HOUSEHOLD 

is  located  beneath  the  floor,  in  a  passage  that  takes  the  air  from 
outdoors  and  after  being  heated,  enters  the  room  through  a 
register  located  in  the  wall. 

Fig.  30  is  still  another  arrangement  known  as  the  direct-indirect 
method  of  heating.  The  radiator  is  placed  in  position,  as  for 
direct  heating,  but  the  air  supply  is  taken  from  outdoors.  The 
radiator  base  is  enclosed  and  a  double  damper  T  regulates  the 
amount  of  air  that  comes  from  the  outside.  When  the  inside 
damper  is  closed  and  the  outside  damper  is  open,  as  is  shown  in 
the  drawing,  the  air  comes  from  outdoors  and  is  heated  as  it 
passes  through  the  radiator  on  its  way  to  the  room.  If  the 
dampers  are  reversed,  the  air  circulates  through  the  radiator  as 
in  the  case  of  direct  radiation. 


FIG.  27. — Two-column  radiator  FIG.  28. — D  i  n  i  n  g-room 

suspended     from     the    wall     by  radiator  containing  a  warm- 

brackets,  ing  oven. 

In  the  use  of  the  direct  or  the  direct-indirect  method  of  heating 
the  principal  object  to  be  attained  is  that  of  ventilation,  but 
quite  generally  the  passages  are  so  arranged  that  the  air  may  be 
taken  from  outdoors  or,  if  desired,  the  air  of  the  house  may  be 
sent  through  the  radiators  to  be  reheated.  In  extremely  cold 
and  windy  weather  it  is  sometimes  difficult  to  keep  the  house  at 
the  desired  temperature  when  all  of  the  air  supply  comes  from 
the  outside.  Under  such  conditions  the  outside  air  is  used  only 
occasionally.  In  mild  weather  it  is  common  to  use  the  outdoor 
air  most  of  the  time.  The  cost  of  heating,  when  these  methods 
are  used,  is  higher  than  by^  direct  radiation,  because  the  air  is 


THE  STEAM  HEATING  PLANT 


31 


being  constantly  changed  in  temperature  from  that  of  the  out- 
side to  70°. 

Radiator  Finishings. — In  steam  and  hot-water  heating  the 
decoration  of  the  radiators  is  a  much  more  important  item  than 
that  of  a  good-looking  surface  or  one  which  will  harmonize  with 
the  setting.  Until  recently  radiator  finishing  has  been  con- 
sidered a  minor  detail  and  the  familiar  bronze  has  been  looked 


FIG.  29. — Ventilation  by  the  indirect 
method  of  heating. 


FIG.  30. — Ventilation  by  the  direct- 
indirect  method  of  heating. 


upon  as  a  standard  covering,  while  painted  radiators  were  con- 
sidered only  a  matter  of  taste.  The  character  of  the  surface  is, 
however,  the  determining  factor  in  the  quantity  of  heat  given 
out  by  radiators.  This  has  been  determined  in  the  experimental 
laboratory  of  the  University  of  Michigan  by  Professor  John  A. 
Allen.  Comparison  was  made  of  bare  cast-iron  radiators  with 
the  same  forms  painted  as  indicated  in  the  following  table.  The 
bare  radiator  was  taken  at  100  per  cent.;  the  other  finishes 


32  MECHANICS  OF  THE  HOUSEHOLD 

are  expressed  in  per   cent,    above   or  below   that  of  the  bare 
radiator. 

Condensing 
capacity, 
per  cent. 

No.  1,  a  cast-iron  radiator,  bare  as  received  from  the  foundry  100 
No.  2,  a  cast-iron  radiator,  coated  with  aluminum  bronze. ...  78 
No.  3,  a  cast-iron  radiator,  three  coats  of  white  enamel  paint. .  102 

No.  4,  a  cast-iron  radiator,  coated  with  copper  bronze 80 

No.  5,  a  cast-iron  radiator,  three  coats  of  green  enamel  paint.  101 
No.  6,  a  cast-iron  radiator,  three  coats  of  black  enamel  paint.  101 

The  author  has  stated  further  that,  "It  might  be  said  in  gen- 
eral that  all  bronzes  reduce  the  heating  effect  of  the  radiator 
about  25  per  cent,  while  lead  paints  and  enamels  give  off  the  same 
amount  of  heat  as  bare  iron.  The  number  of  coats  of  paint  on 
the  radiator  makes  no  difference.  The  last  coat  is  always  the 
determining  factor  in  heat  transmission." 

PIPE  COVERINGS 

All  hot-water  or  steam  pipes  in  the  basement  and  in  other 
places  not  intended  to  be  used  for  heating  should  be  covered 
with  some  form  of  insulating  material.  At  ordinary  working 
temperature  a  square  foot  of  hot  pipe  surface  will  radiate  about 
15  B.t.u.  of  heat  per  minute.  To  prevent  this  loss  of  heat  and 
the  consequent  waste  of  fuel  the  pipes  should  be  covered  with 
some  form  of  insulating  material. 

Pipe  coverings  are  made  of  many  kinds  of  material  and  some 
possess  insulating  properties  that  may  reduce  the  loss  to  as  low 
a  point  as  15  per  cent,  of  the  amount  radiated  by  a  bare  pipe. 
Many  good  insulating  materials  do  not  give  satisfactory  results 
as  pipe  coverings  because  they  do  not  keep  their  shape,  some 
cannot  be  considered  in  the  average  plant  because  of  high  cost. 

Wood-pulp  paper  is  extensively  used  as  a  cheap  covering; 
it  is  a  good  insulator  and  under  ordinary  conditions  makes  a 
satisfactory  covering.  A  more  efficient  and  also  a  more  expensive 
covering  that  is  extensively  used  is  that  made  of  magnesia 
carbonate  and  known  as  magnesia  covering.  Aside  from  these, 
other  forms  made  of  cork,  hair-felt,  asbestos  and  composition 
covering^  are  sometimes  used  in  house-heating  plants. 

In  selecting  a  pipe  covering,  there  should  be  taken  into  account 


THE  STEAM  HEATING  PLANT  33 

not  only  its  insulating  properties  but  its  ability  to  resist  fire, 
dampness  or  breeding  places  for  vermin.  It  rests  entirely  with 
the  owner  whether  he  covers  the  pipes  with  a  combustible  or  an 
incombustible  material  when  the  insulating  properties  are  about 
the  same.  Coverings  made  of  animal  or  vegetable  materials 
under  some  conditions  furnish  a  breeding  place  for  vermin. 

Pipe  coverings  are  made  in  sections  about  3  feet  in  length  and 
from  1  to  1%  inches  in  thickness.  The  sections  are  usually 
cut  in  halves  lengthwise  to  permit  being  put  in  place.  The 
sections  are  covered  with  common  muslin  to  keep  the  material 
in  place  and  sometimes  are  painted  after  being  installed.  Paint- 
ing has  nothing  to  do  with  their  insulating  capabilities,  but  it 
preserves  the  cloth  and  makes  a  neat  appearance.  The  sections 
when  put  in  place  are  secured  by  pasting  one  of  the  loose  edges 
of  the  cloth  to  the  surface.  The  ends  of  the  sections  are  bound 


FIG.  31. — Pipe  covering. 

together  with  strips  of  metal.  Fig.  31  shows  the  appearance  of 
the  pipe  when  the  covering  is  in  place. 

Irregular  surfaces  like  the  body  of  the  furnace,  pipe  connec- 
tions, etc.,  are  insulated  by  coverings  made  from  a  plaster  that 
is  made  expressly  for  such  work.  It  is  known  as  asbestus  plaster. 
The  plaster  may  be  purchased  in  bulk  and  put  in  place  with  a 
trowel.  As  it  is  found  in  the  market  the  plaster  requires  only 
the  addition  of  water  to  put  into  working  form. 

The  value  of  a  pipe  covering  is  not  in  proportion  to  its  thick- 
ness. Experiments  with  pipe  coverings  have  shown  that  a  thick- 
ness of  1%  inches  will  reduce  the  radiation  90  per  cent.,  but 
doubling  the  thickness  reduces  the  loss  only  5  per  cent.  It, 
therefore,  does  not  pay  to  make  a  covering  more  than  1%  inches 
thick. 

Vapor-system  Heating. — This  system  of  heating  is  not  greatly 
different  from  the  steam  plants  already  described  but  it  is 
operated  under  conditions  which  do  not  permit  the  steam  in  the 


34  MECHANICS  OF  THE  HOUSEHOLD 

boiler  to  rise  beyond  a  few  ounces  of  pressure.  Since  the  plant 
is  intended  to  work  at  a  pressure  that  is  scarcely  indicated  by 
an  ordinary  steam  gage,  it  has  been  termed  a  vapor  system  to 
distinguish  it  from  the  pressure  systems  which  employ  steam,  up 
to  5  pounds  or  more  to  the  square  inch.  The  heat  is  trans- 
mitted to  the  radiators  in  the  same  manner  as  in  the  pressure 
systems.  The  heat  of  vaporization  of  steam  is  somewhat  greater 
at  the  boiling  point  of  water  than  at  higher  pressures,  and  the 
lack  of  pressure,  therefore,  increases  its  heating  capacity.  This 
is  shown  in  the  table,  properties  of  steam,  on  page  3.  The 
successful  operation  of  such  a  plant  rests  in  the  delivery  of  the 
vapor  to  the  radiators  at  only  the  slightest  pressure  and  the 
return  of  the  condensate  to  the  boiler  without  noise  or  obstruction 
to  the  circulation  at  the  same  time  ejecting  the  contained  air. 

The  excellence  of  the  system  depends  in  the  greatest  measure 
on  good  design  and  the  employment  of  special  facilities  that 
allow  all  water  to  be  discharged  from  the  radiators  and  returned 
to  the  boiler  without  accumulation  at  any  part  of  the  circulating 
system.  It  requires,  further,  the  discharge  of  the  air  from  the 
system  at  atmospheric  pressure.  -  The  system  is,  therefore,  prac- 
tically pressureless. 

Various  systems  of  vapor  heating  are  sold  under  the  names 
of  their  manufacturers.  Each  possesses  special  appliances  for 
producing  positive  circulation  that  are  advocated  as  features  of 
particular  excellence.  The  vapor  system  of  heating  has  met  with 
a  great  deal  of  favor  as  a  more  nearly  universal  form  of  heating 
than  either  the  pressure-steam  plant  or  the  hot-water  method  of 
heating. 

Fig.  31  a  is  a  diagram  illustrating  the  C.  A.  Dunham  system 
of  vapor  heating.  It  will  be  noticed  that  there  are  no  air  vents 
on  the  radiators.  The  air  from  the  radiators  is  ejected  through 
a  special  form  of  trap  that  is  indicated  in  the  drawing.  These 
traps  permit  the  water  and  air  to  pass  from  the  radiators  but 
close  against  the  slightly  higher  temperature  of  the  vapor.  This 
assures  the  condensation  of  the  vapor  in  the  radiators  and  ex- 
cludes it  from  the  return  pipes.  The  water  returns  to  the  boiler 
in  much  the  same  manner  as  in  the  pressure  systems  already  de- 
scribed but  the  air  escapes  through  the  air  eliminator  as  indi-' 
cated  in  the  drawing.  The  system  is,  therefore,  under  atmos- 


THE  STEAM  HEATING  PLANT 


35 


pheric  pressure  at  this  point  and  only  a  slight  amount  greater 
in  the  boiler. 

The  water  of  condensation  is  returned  to  the  boiler  against 
the  vapor  pressure,  by  a  force  exerted  by  the  column  of  water 
in  the  pipe  connecting  the  air  eliminator  with  the  boiler.  The 


FIG.  31a. — Diagram  showing  the  C.  A.  Dunham  Co.'s  system  of  vapor  heating. 

main  return  is  placed  24  inches  or  more  above  the  water  line  of 
the  boiler.  It  is  the  pressure  of  this  column  that  forces  the 
water  into  the  boiler  through  the  check  valve,  against  the  vapor 
pressure  in  the  boiler. 


36  MECHANICS  OF  THE  HOUSEHOLD 

It  might  be  imagined  that  the  water  in  the  boiler  and  that 
in  the  air-eliminator  pipe  formed  a  "U-tube,"  the  vapor  pressure 
on  the  water  surface  in  the  boiler,  and  the  atmospheric  pressure 
on  the  water  in  the  eliminator  standpipe.  The  slight  vapor  pres- 
sure in  the  boiler  is  counterbalanced  by  a  column  of  water  in  the 
eliminator  pipe.  It  is  this  condition  that  fixes  a  distance  of  24 
inches  from  the  water  line  to  the  return  pipe;  that  is,  the  force 
exerted  by  a  column  of  water  24  inches  high  is  required  to  send 
the  water  into  the  boiler.  * 

The  vapor  pressure  is  controlled  by  means  of  the  pressurestat, 
which  is  an  electrified  Bourdon  spring  pressure  gage,  connected 
up  by  simple  wiring  to  the  damper  motor,  which  may  be  any  form 
of  damper  regulator.  In  residential  work,  the  pressurestat  is  so 
connected  with  a  thermostat,  that  both  pressure  and  temperature 
conditions  operate  and  control  this  damper  regulator,  which  in 
turn  controls  the  draft  and  the  fire. 

The  two  instruments  are  so  connected  that  if  the  pressure 
mounts  to  8  ounces  and  the  pressurestat  caused  the  draft  damper 
to  close  and  the  check  to  open,  the  thermostat  cannot  reverse 
the  damper,  regardless  of  the  temperature  in  the  room,  until 
the  pressure  drops  below  the  limiting  8-ounce  pressure.  Just 
so  long  as  the  pressure  is  below  8  ounces,  the  thermostat  is  the 
master  -in  the  control  of  the  dampers.  The  minute  that  the 
pressure  goes  up  to  8  ounces  then  the  pressurestat  takes  control. 


CHAPTER  II 
THE  HOT-WATER  HEATING  PLANT 

Of  the  various  systems  of  heating  dwellings  that  by  hot-water 
is  considered  by  many  to  be  the  most  satisfactory.  On  account 
of  its  high  specific  heat,  water  at  a  temperature  much  below  the 
boiling  point  furnishes  the  heat  necessary  to  keep  the  tempera- 
ture of  the  house  at  the  desired  degree.  The  temperature  of 
the  radiators  is  generally  much  lower  than  those  heated  by 
steam  but  the  amount  of  radiating  surface  is  greater  than  for 
steam  heating  plants  of  the  same  capacity.  It  is  because  of 
the  relatively  low  temperature  at  which  the  water  is  used,  that 
the  greater  amount  of  heating  surface  is  required. 

One  objection  to  the  use  of  hot  water  as  a  means  of  heating 
is,  that  once  the  heat  of  the  house  is  much  reduced,  the  furnace 
is  a  long  time  in  raising  the  temperature  to  normal.  .This  is 
due  to  the  fact  that  the  temperature  of  the  water  of  the  entire 
system  must  be  uniformly  raised,  because  of  its  continuous  pas- 
sage through  the  heater.  On  the  other  hand,  this  uniformity 
of  the  temperature  of  the  water  prevents  sudden  changes  in 
the  temperature  of  the  house.  Water-heating  plants  work  with 
perfect  quiet  and  may  be  so  regulated  to  suit  the  outside  tem- 
perature that  the  heat  of  the  water  will  just  supply  the  amount 
to  suit  the  prevailing  conditions. 

The  care  required  in  the  management  of  the  boiler  is  less 
than  that  required  in  the  steam  plant  because  of  the  fewer 
appliances  necessary  for  its  safe  operation.  Another  advantage 
in  the  use  of  the  hot-water  plant  is  its  adaptability  to  the 
temperature  conditions  during  the  chilly  weather  of  early  fall  and 
late  spring,  when  a  very  small  amount  of  heat  is  required.  At 
such  times  the  temperature  of  the  radiators  is  but  a  few  degrees 
warmer  than  the  outside  air.  The  amount  of  attention  necessary 
for  maintaining  the  proper  furnace  fire  under  such  conditions  is 
less  then  for  any  other  form  of  heating.  The  increasing  use  of 

37 


38 


MECHANICS  OF  THE  HOUSEHOLD 


Expansion 
Tank 


Badiator 


the  hot-water  plant  for  heating  the  average-sized  dwelling  attests 
to  its  excellence  in  service. 

The  Low-pressure  Hot-water  System. — A  hot-water  system 
consists  of  a  heater,  in  which  the  water  receives  its  supply  of 
heat,  the  circulating  pipes  for  conducting  the  heated  water  to 
and  from  the  radiators  that  supply  heat  to  the  rooms,  and  the 
expansion  tank  that  receives  the  excess  of  water  caused  when  the 

temperature  is  raised  from  nor- 
mal to  the  working  degree.  In 
addition  to  the  parts  named  there 
are  a  number  of  appliances  to 
be  described  later,  that  are  re- 
quired to  make  the  system  com- 
plete. 

A  hot-water  plant  of  the  sim- 
plest 'form  is  shown  in  Fig.  32. 
The  illustration  presents  each  of 
the  features  mentioned  above, 
as  in  a  working  plant.  The 
different  parts  are  shown  cut 
across  through  the  middle,  the 
black  portion  representing  water. 
Not  only  does  the  water  fill  th*e 
entire  system  but  appears  in  the 
expansion  tank  when  the  plant 
is  cold. 

Hot-water  heaters  are  quite 
generally  in  the  form  of  intern- 
ally fired  boilers.  The  fire-box 

occupies  a  place  inside  the  boiler  and  is  surrounded,  except  at 
the  bottom,  by  the  water  space.  Commonly,  these  boilers  are 
made  of  cast  iron  and  are  constructed  in  sections,  the  same  as 
the  steam  boiler  shown  in  Fig.  16.  Manufacturers  sell  a  single 
style  for  either  steam  or  hot- water  heating.  The  boiler  in  Fig. 
32  is  cylindrical  in  form.  It  is  made  of  wrought  iron  and  con- 
tains a  large  number  of  vertical  tubes  through  which  the  heat 
from  the  furnace  must  pass  on  its  way  to  the  chimney. 

As  the  water  is  heated  it  expands  and  rises  to  the  top  of  the 
boiler  because  of  its  decreased  weight.     Since  the  water  in  the 


FIG.  32. — Diagram  of  a  simple  form 
of  hot-water  heating  plant. 


THE  HOT-WATER  HEATING  PLANT  39 

radiator  is  really  a  part  of  the  same  body  of  water,  the  heated 
portion  rises  through  the  supply  pipe  to  the  top  of  the  radiator. 
As  the  hot  water  rises  in  the  radiator,  it  displaces  an  equal  amount 
of  cold  water,  which  enters  the  boiler  at  the  bottom.  This 
displacement  is  constant  and  produces  a  circulation  that  begins 
as  soon  as  the  fire  is  started  and  varies  with  the  difference  in 
temperature  between  the  hot  water  leaving  the  boiler  at  the  top 
and  the  cold  water  entering  at  the  bottom. 

As  the  water  in  the  system  is  heated  and  expands,  there  must 
be  some  provision  made  to  receive  the  enlarging  volume.  In 
this  arrangement  a  pipe  connects  the  bottom  of  the  boiler  with 
the  expansion  tank  located  at  a  point  above  the  radiator.  Under 
the  conditions  represented  in  the  drawing  the  water  does  not 
circulate  through  the  tank  and  as  a  consequence  the  water  it 
contains  is  always  cold. 

In  raising  its  temperature,  water  absorbs  more  heat  than  any 
other  fluid  and  on  cooling  it  gives  up  an  equal  amount.  As 
a  consequence  it  furnishes,  an  excellent  vehicle  for  transmitting 
the  heat  of  the  furnace  to  the  rooms  to  be  heated.  Water, 
however,  is  a  poor  conductor  and  receives  its  heat  by  coming 
directly  into  contact  with  the  hot  surfaces  of  the  furnace,  and 
gives  it  up  by  direct  contact  with  the  radiator  walls.  To  trans- 
mit heat  rapidly  and  maintain  a  high  radiator  temperatur 
the  circulation  of  the  water  in  the  system  must  be  the  be 
possible.  The  connecting  pipes  between  the  boiler  and  the  radi- 
ators must  be  as  direct  as  circumstances  will  permit  and  the 
amount  of  radiating  surface  in  each  room  must  be  sufficient  to 
easily  give  up  an  ample  supply  of  heat.  Even  though  the  furnace 
is  able  to  furnish  a  plentiful  supply  of  heat  to  warm  the  house, 
it  cannot  be  transmitted  to  the  rooms  unless  there  is  sufficient 
radiating  surface.  A  plant  might  prove  unsatisfactory  either 
because  of  a  furnace  too  small  to  furnish  the  necessary  heat  or 
from  an  insufficient  amount  of  radiating  surfacev  Yet  another 
factor  in  the  design  of  a  plant  is  that  of  the  conducting  pipes. 
Both  the  boiler  and  the  radiators  might  be  in  the  right  proportion 
to  produce  a  good  plant,  but  if* the  distributing  pipes  are  too  s.mall 
to  carry  the  water  required,  or  the  circulation  is  retarded  by  man^ 
turns  and  long  runs,  the  plant  may  fail  to  give  satisfaction. 

Fig.  33  shows  a  complete  hot-water  plant  adapted  to  a  dwelling. 


*t=> 
id    g* 

"j 

v 


40 


MECHANICS  OF  THE  HOUSEHOLD 


It  is  just  such  a  plant  as  is  commonly  installed  in  the  average- 
sized  house  but  without  any  of  the  appliances  used  for  auto- 
matic control  of  temperature.  The  regulation  of  the  temperature 
is  made  entirely  by  hand,  in  so  governing  the  fire  as  to  provide 
the  required  amount  of  heat.  In  the  drawing  the  supply  and 
return  pipes  may  be  traced  to  the  radiators  as  in  the  case  of  the 
simple  plant.  The  supply  pipe  from  the  top  of  the  boiler  branches 
into  two  circuits  to  provide  the  water  for  the  two  groups  of  radi- 
ators at  the  right  and  left  side  of  the  house.  To  provide  any 


FIG.  33. — The  low-pressure  hot-water  heating  system  applied  to  a  small  dwelling. 

radiator  with  hot  water,  a  pipe  is  taken  from  the  main  supply  pipe 
and  passing  through  the  radiator  it  is  brought  back  and  connected 
with  the  return  pipe  which  conducts  the  water  Back  to  the  boiler. 
The  expansion  tank  is  located  in  the  bathroom  near  the  ceiling. 
It  is  connected  with  the  circulating  system  by  a  single  pipe  which 
joins  the  supply  pipe  as  it  enters  the  radiator  located  in  the 
kitchen.  Like  the  expansion  tank  in  Fig.  31  the  water  it  con- 
tains is  always  cold.  It  is  provided  with  a  gage-glass  which 
shows  the  level  of  the  water  in  the  tank  and  an  overflow  pipe 
which  discharges  into  the  bathtub,  in  case  of  an  overflow.  An 
overflow  pipe  must  always  be  provided  to  take  care  of  the  sur- 


THE  HOT-WATER  HEATING  PLANT  41 

plus  when  the  water  in  the  system  becomes  overheated.  This 
does  not  often  occur  but  the  provision  must  be  made  for  the 
emergency.  The  overflow  pipe  is  frequently  connected  directly 
with  the  sewer  or  discharged  at  some  convenient  place  in  the 
basement. 

The  High-pressure  Hot-water  System. — In  the  hot-water 
plant  described  the  expansion  tank  is  open  to  the  air  and  the 
water  in  the  system  is  subjected  to  the  pressure  of  the  atmosphere 
alone.  The  heat  of  the  furnace  may  be  sufficiently  great  to 
bring  the  entire  volume  of  water  of  the  system  to  the  boiling 
point  and  cause  it  to  overflow  but  the  temperature  of  the  water 
cannot  rise  much  above  the  boiling  point  due  to  the  pressure  of 
the  atmosphere. 

If  the  expansion  tank  is  closed,  the  pressure  generated  by  the 
expanding  water  and  the  formation  of  steam  will  permit  the 
water  to  reach  a  much  higher  temperature,  In  the  table  of 
temperatures  and  pressures  of  water  on  page  3,  it  will  be 
seen  that  should  the  pressure  rise  to  10  pounds,  that  is,  10  pounds 
above  the  pressure  of  the  atmosphere,  the  temperature  of  the 
water  would  be. very  nearly  240°F.  (239.4°F.).  The  difference 
in  heating  effect  in  hot-water  heating  plants  under  the  two  con- 
ditions is  very  marked.  In  the  low-pressure  system  the  tempera- 
ture of  the  radiators  cannot  be  above  212°  but  the  high-pressure 
system  set  for  10  pounds  pressure  will  heat  the  radiators  to  240°, 
and  a  still  higher  pressure  would  give  a  correspondingly  higher 
temperature.  The  amount  of  heat  radiated  by  a  hot  body  is  in 
proportion  to  the  difference  in  temperature  between  the  body 
and  the  surrounding  air.  If  we  consider  the  surrounding  air 
at  60°  the  difference  in  amount  of  heat-radiation  capacity  of 
the  two  radiators  would  be  as  180  is  to  132.  The  advantage 
of  the  high-pressure  system  lies  in  its  ability  to  heat  a  given 
space  with  less  radiating  surface  than  the  low-pressure  system. 

In  Fig.  34  is  illustrated  an  application  of  a  simple  and  efficient 
valve  arrangement  that  converts  a  low-pressure  hot-water  system 
into  a  h/gh-pressure  system  without  changing  in  any  way  the 
piping  or  radiators.  The  drawing  shows  the  boiler  and  two 
radiators  connected  as  for  a  low-pressure  system,  "but  attached 
to  the  end  of  the  pipe  as  it  enters  the  expansion  tank  is  a  safety 
valve  B  and  a  check  valve  A,  as  indicated  in  the  enlarged 


42 


MECHANICS  OF  THE  HOUSEHOLD 


figure  of  the  valve.  The  safety  valve  is  intended  to  allow  the 
water  to  escape  into  the  expansion  tank  when  the  pressure  in 
the  system  reaches  a  certain  point  for  which  the  valve  is  set. 
The  check  valve  A  permits  the  water  to  reenter  the  system 
from  the  tank  whenever  the  pressure  is  restored  to  its  normal 
amount. 


FIG.  34. — The  high-pressure  system  of  hot-water  heating. 

Suppose  that  such  a  system  is  working  as  a  low-pressure  plant. 
The  hot  water  from  the  top  of  the  boiler  is  flowing  to  the  radia- 
tors through  the  supply  pipe  and  the  displaced  cooler  water  is 
returning  to  the  bottom  of  the  boiler  through  the  return  pipe  as 
in  the  other  plants  described.  It  is  now  found  that  the  radiators 
are  hot  sufficiently  large  to  heat  the  rooms  to  the  desired  de- 
gree except  when  the  furnace  is  fired  very  heavily.  It  is  always 


THE  HOT-WATER  HEATING  PLANT  43 

poor  economy  to  keep  a  very  hot  fire  in  any  kind  of  a  heater,  be- 
cause a  hot  fire  sends  most  of  its  heat  up  the  chimney.  If  the 
radiators  could  be  safely  raised  in  temperature,  they  would,  of 
course,  give  out  more  heat  and  as  a  result  the  rooms  would  be  more 
quickly  heated  and  kept  at  the  required  temperature  with  less  ef- 
fort by  the  furnace.  The  difficulty  in  this  case  lies  solely  in 
there  being  insufficient  radiator  surface  to  supply  heat  as  fast 
as  required. 

The  increase  in  radiator  temperature  is  accomplished  by  the 
pressure  regulating  valve  B,  attached  to  the  end  of  the  pipe  as 
it  enters  the  expansion  tank.  The  expansion  tank  with  the  regu- 
lating valve  is  shown  enlarged  at  the  left  of  the  figure.  The  valve 
B  is  kept  closed  by  a  weight  marked  Wy  that  is  intended  to.  hold 
back  a  pressure  of  say  10  pounds  to  the  square  inch.  A  pressure 
of  10  pounds  will  require  a  temperature  of  practically  240°F. 
(see  table  on  page  3).  The  check  valve  A  is  kept  closed  by 
the  pressure  from  the  inside  of  the  system.  When  the  pressure 
of  the  water  goes  above  10  pounds — or  the  amount  of  the  weight 
is  intended  to  hold  back — the  valve  is  lifted  and  an  amount  of 
water  escapes  through  the  valve  B  into  the  tank,  sufficient  to 
relieve  the  pressure.  Should  enough  water  be  forced  out  of  the 
system  to  fill  the  tank  to  the  top  of  the  overflow  pipe,  the  over- 
flow water  is  discharged  through  this  pipe  into  the  sink  in  the 
basement. 

When  the  house  has  become  thoroughly  warmed,  the  demand 
for  a  high  radiator  temperature  is  reduced,  the  furnace  drafts 
are  closed,  the  water  in  the  system  cools  and  as  it  shrinks  the 
system  will  not  be  completely  filled.  It  is  then  necessary  to 
take  back  from  the  tank  the  water  that  has  been  forced  out 
by  excess  pressure.  It  is  here  that  the  check  valve  comes  into 
use.  So  long  as  there  is  pressure  on  the  pipes,  this  valve  is  held 
shut  and  no  water  can  escape,  but  as  the  inside  pressure  is 
released  by  the  cooling  there  will  come  a  point  where  the  water 
in  the  tank  will  flow  back  through  the  valve  A  and  fill  the  system. 
This  is  the  type  of  valve  used  by  the  Andrews  Heating  Co. 
and  designated  a  regurgitating  valve.  In  practice  it  gives  ex- 
cellent service.  The  only  danger  of  excessive  pressure  in  the 
use  of  this  device  is  the  possibility  of  the  valve  becoming  stuck 
to  the  seat  through  disuse.  Any  possible  danger  from  such  an 


44  MECHANICS  OF  THE  HOUSEHOLD 

occurrence  may  be  eliminated  by  the  occasional  lifting  of  the 
valve  by  hand. 

Heating-plant  Design. — A  heating  plant  should  be  designed  by 
a  person  of  experience.  No  set  of  rules  has  yet  been  devised  that 
will  meet  every  condition.  Carpenter's  rules  given  on  page  25 
serve  for  hot  water  as  well  as  for  steam  as  a  means  of  determining 
the  radiating  surface  required  for  an  ordinary  building,  but  the 
rules  do  not  take  into  account  the  method  of  construction  of 
the  house  and  the  consequent  extra  radiation  demanded  for 
poorly  constructed  buildings.  In  many  cases  the  designer  must 
rely  on  experience  as  a  guide  where  the  rules  will  not  apply. 
In  the  case  usually  encountered,  however,  the  rules  given  will 
meet  the  conditions. 

What  was  said  regarding  the  size  of  steam  boilers  required 
for  definite  amounts  of  heating  surfaces,  applies  with  equal  force 
to  hot-water  boilers,  because  house-heating  boilers  are  commonly 
used  for  either  steam  or  hot-water  heating.  There  are  no  es- 
tablished rules'  for  determining  the  heating  capacities  of  house- 
heating  boilers.  Manufacturers'  ratings  are  usually  low.  There 
are  some  manufacturers  who  make  honest  ratings  for  their  boilers 
but  they  are  in  the  minority.  When  the  heating  capacity  of  a 
boiler  is  not  known  from  experience,  the  only  safeguard  against 
installing  a  boiler  too  small  for  the  radiators  to  be  heated,  is 
to  require  a  guarantee  that  the  plant  will  give  satisfaction  when 
in  operation  and  when  considered  necessary  a  certain  percentage 
of  the  contract  price  should  be  withheld  until  the  plant  proves 
itself  by  actual  trial. 

Overhead  System  of  Hot-water  Heating. — In  Fig.  35  is  illus- 
trated another  system  of  high-pressure  hot-water  heating  that 
corresponds  to  the  overhead  system  of  steam  heating.  It  differs 
from  the  high-pressure  system  already  described  in  the  method 
of  distribution  and  in  the  radiator  connections. 

The  flow  pipe  is  taken  to  the  attic  and  there  joined  to  the 
expansion  tank  as  a  point  of  distribution.  On  the  expansion 
tank  is  a  safety  valve  set  at  10  or  more  pounds  pressure.  The 
flow  of  the  water  is  all  downward  toward  the  radiators.  The 
circulation  through  the  radiators  is  also  different  from  the  other 
plants  described.  The  supply  pipe  joins  directly  to  the  return 
pipe  and  the  connections  to  the  radiators  are  made  at  the  top  and 


THE  HOT-WATER  HEATING  PLANT 


45 


bottom  of  the  same  end.  The  circulation  through  the  radiators 
in  this  case  is  due  to  the  difference  in  gravitational  effect  between 
the  hot  and  colder  water  at  the  top  and  bottom  of  the  -radiator. 
The  system  requires  no  air  vents  on  the  radiators  as  all  air  that 
might  collect  in  the  system  goes  up  to  the  expansion  tank.  The 
safety  valve  on  the  expansion  tank  in  this  case  is  the  common 
lever  type.  The  overflow  should  empty  into  the  sewer  and  be 
pitched  to  prevent  any  water  being  retained  in  the  discharge 


FIG.  35. — The  overhead  system  of  hot-water  heating. 

pipe.  If  water  should  be  retained  in  this  pipe  and  should  freeze, 
the  system  would  become  dangerous,  because  of  the  possibility  of 
high  pressures  from  a  hot  fire. 

Expansion  Tanks. — Fig.  36  is  a  form  of  expansion  tank  in 
common  use.  It  may  be  used  for  either  the  high-  or  low-pressure 
system.  The  body  of  the  tank  is  made  of  galvanized  iron  and 
is  made  to  stand  a  considerable  amount  of  pressure.  The  gage- 
glass  is  attached  at  B,  and  the  overflow  at  0.  The  pipe  E  con- 
nects the  tank  with  the  circulating  system  and  D  connects  with 
the  cold-water  supply  as  a  convenience  for  filling  the  system 


46 


MECHANICS  OF  THE  HOUSEHOLD 


with  water.  The  object  in  placing  the  stop-cock  D  near  the 
expansion  tank  is  to  avoid  overflowing  the  system  in  filling. 
The  overflow  pipe,  as  stated  above,  is  most  conveniently  con- 
nected with  the  sewer,  into  which  the  water  will  run  in  case  of 
an  overflow,  but  the  other  methods  shown  are  commonly  used. 
There  should  be  no  valve  in  this  pipe  nor  in  the  pipe  E. 


FIG.  36. — The  expansion 
tank. 


FIG.  37. — When  the  expansion  tank  of  a  hot- 
water  heating  system  must  be  so  located  that 
it  is  apt  to  freeze,  it  must  be  piped  as  a  radiator. 


The  expansion  tank  must  be  so  located  that  there  will  be  no 
danger  of  freezing.  Should  it  be  necessary  to  place  the  tank  in  the 
attic  or  where  freezing  is  possible,  the  tank  must  be  so  connected 
as  to  become  a  part  of  the  circulating  system.  Such  an  arrange- 
ment is  shown  in  Fig.  37.  The  expansion  tank  is  connected  with 
a  supply  and  return  pipe  as  a  radiator.  This  arrangement  is 
sometimes  used  but  it  is  not  desirable.  It  is  wasteful  of  heat 
and  there  is  always  a  possibility  of  freezing  in  case  the  fire  in 


THE  HOT-WATER  HEATING  PLANT  '%. 

the  furnace  is  extinguished  a  sufficient  time  to  allow  the  water 
to  grow  cold. 

Any  possibility  of  danger  from  excessive  pressures  in  either 
the  low-pressure  or  the  high-pressure  system  must  originate  in 
the  expansion  tank.  It  is,  therefore,  desired  to  again  mention 
the  possible  causes  of  danger.  Any  closed-tank  system  is  liable 
to  become  overheated.  The  expansive  force  of  water  is  irresist- 
ible and  unless  some  means  is  taken  to  prevent  excessive  pres- 
sure some  part  of  the  apparatus  is  apt  to  burst.  No  closed- 
tank  system  should  be  used  without  a  safety  valve. 

The  low-pressure  or  open-tank  system  requires  no  safety  ap- 
pliances. So  long  as  there  is  open  communication  between  the 
tank  and  the  boiler  the  pressure  cannot  rise  but  slightly  above 
that  of  the  atmosphere.  There  is  only  one  cause  that  will  lead 
to  high  pressure  in  such  a  system.  If  the  pipe  connecting  the 
expansion  tank  is  stopped  an  excessive  pressure  might  generate. 
There  is  little  or  no  danger  of  this  happening. 

In  the  closed-tank  system  the  expansion  tank  should  be  of 
greater  capacity  than  for  the  open-tank  system.  Its  size  is  com- 
monly about  one-ninth  of  the  volume  of  water  used.  The  larger 
tank  is  necessary  to  prevent  too  rapid  rise  of  pressure  as  the  tem- 
perature of  the  water  rises.  The  air  in  the  tank  acts  as  a 
cushion  against  which  the  pressure  of  the  expanding  water  is 
exerted. 

The  extended  use  of  hot-water  heating  has  led  to  the  invention 
of  many  appliances  for  the  improvement  of  the  circulation  and 
heating  effects.  Pulsation  valves  are  used  for  retaining  the  water 
in  the  boiler  until  a  definite  pressure  has  been  attained  that  will 
lift  the  valve  long  enough  to  dissipate  the  pressure.  Many  of 
these  systems  possess  merit  and  some  of  them  are  great  improve- 
ments over  the  simple  plant. 

Radiator  Connection. — The  method  of  connecting  the  radiators 
to  the  distributing  pipes  depends  entirely  on  local  conditions. 
In  a  well-balanced  system  any  of  the  methods  shown  in  Figs.  38, 
39  or  40  might  be  used  with  good  heating  effects.  The  method 
of  attaching  the  supply  pipe  to  the  radiator  is,  however,  an  im- 
portant factor  in  case  of  accumulation  of  air.  In  Fig.  41  is 
shown  the  form  of  connection  most  commonly  used.  The  draw- 
ing is  intended  to  represent  a  cast-iron  radiator  with  the  valve 


MECHANICS  OF  THE  HOUSEHOLD 


at  D,  and  the  air  vent  at  B.  Should  air  collect  in  the  radiator 
it  will  rise  to  the  top  and  displace  the  water.  The  water  will 
continue  to  circulate  and  heat  as  much  of  the  radiator  as  is  in 
contact  with  the  water,  but  that  part  not  in  contact  will  receive 


FIG.  38.  FIG.  39.  FIG.  40. 

FIGS.  38  TO  40. — Various  methods  of  attaching  the  supply  and  return  pipes  to 

hot-water  radiators. 

no  heat  from  the  water  and  will,  therefore,  fail  to  fulfill  its 
function.  As  soon  as  the  air  vent  is  opened  the  air  will  escape 
and  allow  the  water  to  entirely  fill  the  space. 


FIG.  41.—  The  effect  of  accumu- 
lation  of  air  in  a  hot-water  radiator 
with  bottom  connections. 


FIG.  42.  —  With  this  method  of  connec- 
tions,  if  the  air  collects  sufficiently  to  force 
the  water  down  to  the  level  L,  circulation 
will  stop. 


In  Fig.  42  a  much  different  condition  exists,  when  air  accumu- 
lates. In  this  mode  of  connection  the  water  enters  through  the 
valve  F,  and  escapes  at  the  bottom  of  the  opposite  end.  When 
air  fills  the  radiator  to  the  line  L,  the  circulation  is  stopped  and 
the  radiator  will  grow  cold. 


THE  HOT-WATER  HEATING  PLANT 


49 


The  position  of  the  valve  on  these  radiators  is  of  little  conse- 
quence. The  valve  is  intended  merely  to  interrupt  the  flow  of 
the  water  and  may  occupy  a  place  on  either  end  of  the  radiator 
with  the  same  result. 

Hot-water  Radiators. — Radiators  for  hot-water  heating  are 
most  commonly  of  cast  iron  and  in  appearance  are  the  same  as 
those  used  for  steam  heating.  The  only  difference  in  the  two 
forms  is  in  the  openings  between  the  sections.  Those  intended 
for  steam  have  an  opening  at  the  bottom  joining  the  sections; 
while  those  for  hot  water  have  openings  at  both  top  and  bottom 
to  permit  circulation  of  the  water. 

Hot-water  Radiator  Valves.— Valves  for  hot-water  radiators 
differ  materially  from  those  used  on  steam  radiators.  Figs.  43 


FIG.  43. — The  hot-water  radia- 
tor valve. 


FIG.  43a. — Details  of  con- 
struction of  the  hot-water 
radiator  valve. 


and  43a  show  the  outside  appearance  and  the  mechanical  arrange- 
ment of  the  parts  of  the  Ohio  hot-water  valve.  The  part  A  in 
Fig.  43a  is  a  hollow  brass  cylinder  attached  to  the  valve-stem, 
one  side  of  which  has  been  removed.  When  it  is  desired  to  shut 
off  the  supply  of  heat  the  handle  of  the  valve  is  given  one-quarter 
turn  and  the  part  A  covers  the  opening' to  the  inlet  pipe.  The 
supply  of  water  being  shut  off,  the  radiator  gradually  cools. 
When  the  valve  is  closed  a  small  amount  of  water  is  admitted  to 
the  radiator  through  a  J^-inch  hole  in  the  piece  A  to  prevent  the 
possibility  of  freezing. 

Air  Vents.— In  the  use  of  the  systems  of  hot-water  heating 
described,  every  radiator  'must  be  supplied  with  an  air  vent  of 
some  kind  to  take  away 'the  trapped  air  which  accumulates 
through  use.  Any  kind  of  a  valve  will  serve  as  a  vent  for  hand 


50  MECHANICS  OF  THE  HOUSEHOLD 

regulation  and  generally  such  a  cock  as  is  shown  in  Fig.  10  is 
employed. 

Automatic  Hot-water  Air  Vents. — It  is  sometimes  desired  to 
use  automatic  air  vents  on  hot- water  radiators.  For  such  work 
a  vent  is  used  that  remains  closed  as  long  as  water  is  present  and 
will  open  when  the  water  is  displaced  by  the  accumulating  air, 
but  will  again  close  when  the  air  is  discharged.  In  such  vents 
the  valve  is  controlled  by  a  float,  the  buoyancy  of  the  float  when 
surrounded  by  water  serving  to  keep  the  valve  closed.  These 
vents  are  not  so  positive  in  their  action  as  automatic  air  vents 
for  steam.  The  change  in  temperature  which  controls  the  steam 
vent  does  not  take  place  with  hot  water.  The  automatic  hot- 
c  water  vents  are  not  perfectly  reliable.  They 

E  may  work  with  entire  satisfaction  for  a  long  time 
and  then  fail  from  very  slight  cause.  The  failure 
of  a  hot- water  vent  is  generally  discovered  by  find- 
ing a  pool  of  water  on  the  floor  or  a  wet  spot  on 
the  ceiling  or  wall  of  the  floor  below. 

•ne  type  of  tke  automatic  hot-water  vent  that 
H  has  proven  quite  successful  is  shown  in  Fig.  44.' 
The  threaded  lug  is  screwed  into  the  radiator  at 
tomatic4air~vent  tne  Pr°Per  point.  As  the  water  enters  the  radia- 
for  hot-water  ra-  tor  the  air  is  discharged  through  the  vent,  escap- 
ing at  the  opening  C.  When  the  water  has  risen 
to  a  sufficient  height  it  enters  the  openings  G  and  H  until  enough 
is  present  to  raise  the  float  A.  The  pointed  stem  attached  closed 
the  hole  C  with  sufficient  force  to  make  an  air-tight  joint.  The 
float  A  is  a  very  light  copper  cylinder.  Its  buoyancy  supplies 
the  force  to  close  the  vent  and  its  weight  opens  the  vent  when 
the  water  is  displaced  by  air.  It  will  be  readily  seen  that  very 
slight  cause  might  prevent  the  performance  of  its  duty. 


v 


CHAPTER  III 


THE  HOT-AIR  FURNACE 

Of  the  methods  of  heating  dwellings  other  than  by  stoves,  that 
of  the  hot-air  furnace  is  the  most  common.  Of  the  various  modes 
of  furnace  heating  it  is  the  least  expensive  in  first  cost  and  most 
rapid  in  effect.  In  the  use  of  steam  heat,  the  water  in  the  boiler 
must  be  vaporized  before  its  heat  is  available.  With  hot-water 
heating,  the  whole  mass  of  water  in  the  entire  system  must  be 
raised  considerably  in  temperature  before  its  heat  can  affect^  the 
temperature  of  the  rooms,  and  consequently  in  first  effect  it  is 
very  slow.  In  the  use  of  the  hot-air  furnace  the  heat  from  the 
register  begins  to  warm  the  rooms  when  the  fire  is  started. 

Hot-air  furnaces  are  made  by  manufacturing  companies  in  a 
great  variety  of  styles  and  forms  to  suit  purposes  of  every  kind. 
In  practice  the  furnace  is  built  in  sizes,  to  heat  a  definite  amount 
of  cubical  space.  The  maker  designs  a  furnace  to  heat  a  certain 
number  of  cubic  feet  of  space  contained  in  a  building.  It  must 
be  sufficiently  large  to  keep  the  temperature  at  70°F.  on  the 
coldest  nights  of  winter  when  the  wind  is  blowing  a  gale.  It  is 
evident  that  with  the  variable  factors  entering  the  problem,  the 
designer  must  be  a  person  of  experience  in  order  that  the  furnace 
meet  the  requirements. 

The  following  table  taken  from  a  manufacturer's  catalogue 
shows  the  method  of  adapting  the  product  of  the  maker  to  any 


Furnace  inirnbGr               •  • 

1 

2 

3 

4 

5 

Weight  without  casing,  Ib. 

984 

1,111 

1,340 

1,531 

1,934 

Estimated  capacities  in 
cubic  feet                

8,000 
to 
12,000 

12,000 
to 
20,000 

20,000 
to 
35,000 

35,000 
to 
60,000 

60,000 
to 
100,000 

Capacity    in    number    of 
rooms  of  ordinary  size  in 
residence  heating      .... 

3  to  5 

5  to  7 

7  to  9 

9  to  12 

12  to  15 

51 


52 


MECHANICS  OF  THE  HOUSEHOLD 


size  of  dwelling.  The  volume  of  the  house  is  calculated  in  cubic 
feet  and  from  this  result  the  size  of  furnace  most  nearly  suited 
is  selected  from  the  table. 


CONSTRUCTION 

The  furnace,  in  general  construction,  consists  of  a  cast-iron 
fire-box  with  its  heating  surfaces,  through  which  the  flames  and 
heated  gases  from  the  fire  pass,  on  the  way  to  the  chimney;  these 
with  the  passages  and  heating  surfaces  for  heating  the  air  compose 

the  essential  features.  Fig.  45 
shows  such  a  furnace  with  the 
sides  broken  away  to  show  the 
internal  construction.  The 
flames  and  gases  from  the  fire- 
box F  circulate  through  the  cast- 
iron  drum  D  and  are  discharged 
at  C  to  the  chimney.  The  drum 
D  is  made  in  such  form  that  it 
presents  to  the  heat  from  the 
fire  a  large  amount  of  heating 
surface  and  at  the  same  time 
offers  as  little  opposition  as 
possible  to  the  'furnace  draft. 
The  air  to  be  heated  enters  the 
furnace  through  the  cold  air  dugt 
at  the  bottom,  and  after  circu- 
lating through  the  drum,  passes 

out  at  the  openings  R  to  the  conducting  pipejs.  The  cast-iron 
box  W  is  a  water  tank  that  should  be  attached  to  eve'ry  hot-air 
furnace.  The  water  contained  in  the  tank  is  for  humidifying 
the  air  as  it  passes  through  the  furnace.  In  this  furnace  the 
outside  casing  is  of  sheet  iron,  reinforced  w^th  wrought-iron 
flanges.  The  front,  which  contains  the  doors  of  the  fire-box, 
ash-pit,  etc.,  are  of  cast  iron  of  ornamented  design. 

As  the  air  to  be  heated  passes  through  the  furnace  it  receives 
part  of  its  warmth  by  radiation  but  most  of  it  is  absorbed  by 
coming  directly  into  contact  with  the  heating  surfaces*  Since  air 
is  a  poor  conductor  of  heat  its  temperature  is  raised  very  slowly; 


FIG.  45. — Interior  view  of  a  hot-air 
furnace. 


THE  HOT-AIR  FURNACE  53 

it  should,  therefore,  be  kept  in  contact  with  the  heating  surfaces 
as  long  as  possible  to  insure  an  economical  furnace.  In  common 
practice  the  ratio  of  heating  surface  to  grate  surface  average  35 
to  1;  that  is,  for  each  square  foot  of  grate  surface  there  is  35 
square  feet  of  heating  surface  to  warm  the  passing  air.  Should 
this  ratio  be  increased  to  50  to  1  the  efficiency  of  the  furnace 
would  be  much  improved. 

If  the  ratio  of  heating  surface  to  the  grate  surface  is  too  small 
for  its  requirements,  the  temperature  of  the  air-heating  surfaces 
must  be  very  high  to  provide  the  desired  amount  of  heat.  Under 
such  a  condition  the  efficiency  of  the  furnace  would  be  low,  since 
in  all  cases  where  rapid  combustion  is  required  the  available 
amount  of  heat  per  pound  of  coal  consumed  is  low.  With  a 
large  amount  of  heating  surface,  the  air  remains  in  contact  with 
the  hot  surface  a  relatively  longer  period  and  the  desired  tempera- 
ture is  reached  with  the  expenditure  of  a  smaller  amount  of  fuel. 
A  momentary  exposure  of  the  air  to  a  red-hot  surface  is  far  less 
effective  than  a  prolonged  contact  with  a  surface  having  only  a 
moderate  temperature.  Time  is  an  element  of  great  importance 
in  heating  air.  In  considering  the  relative  merits  of  two  furnaces 
with  the  same  amount  of  grate  surface,  that  with  the  larger 
amount  of  heating  surface  will  evidently  be  the  most  efficient. 

The  supply  of  heat  comes  primarily  from  the  burning  coal  on 
the  furnace  grate.  The  grate  surface  should  be  large  enough  in 
area  to  permit  the  required  quantity  of  heat  to  be  generated  by 
the  burning  fuel  with  a  moderate  fire.  If  the  grate  surface  is  too 
small  for  the  required  purpose,  a  hot  fire  will  be  necessary,  when 
the  normal  amount  of  heat  is  demanded  by  the  house.  During 
extremely  cold  weather,  particularly  when  accompanied  by  high 
wind,  the  extra  heat  demanded  to  keep  the  house  at  the  desired 
temperature  makes  necessary  the  use  of  an  amount  of  fuel  that 
cannot  be  burned  on  the  grate  unless  the  fire  is  forced.  Hot  fires 
can  be  kept  up  only  at  the  expense  of  a  large  amount  of  heat,  and 
the  resultant  efficiency  of  the  furnace  is  reduced. 

High  furnace  temperatures  are  always  attended  by  a  large 
loss  of  heat.  The  vastly  greater  quantity  of  air  necessary  to 
create  the  combustion,  the  high  temperature  of  the  chimney  gases 
and  the  increased  velocity  of  the  heated  gases  through  the 
furnace,  all  tend  to  increase  the  amount  of  heat  that  is  sent  up 


54  MECHANICS  OF  THE  HOUSEHOLD 

the  chimney,  and  to  decrease  the  percentage  of  heat  that 
is  delivered  by  the  furnace.  In  order  to  heat  the  house  eco- 
nomically the  furnace  must  be  large  enough  to  easily  generate 
the  required  amount  of  heat  demanded  in  the  most  severe 
weather. 

Furnace -gas  Leaks. — The  presence  of  furnace  gas  in  the  atmos- 
phere of  a  house  is  not  only  annoying  but  may  be  a  source  of 
danger.  Gas  leaks  are  commonly  due  to  the  imperfect  union  of 
the  various  parts  of  which  the  furnace  is  composed. 

Cast-iron  furnaces  are  constructed  in  sections  that  are  as- 
sembled to  form  a  complete  plant.  In  assembling,  the  various 
parts  of  contact  must  be  carefully  joined  to  prevent  the  gases  in 
the  fire-box  from  escaping  into  the  air-heating  space.  In  the 
manufacture  of  cast-iron  furnaces  it  is  practically  impossible  to 
form  gas-tight  joints  by  the  contact  of  the  metal  alone.  In  the 
erection  of  the  furnace  all  doubtful  joints  are  filled  with  stove 
putty.  Furnaces  of  good  design  require  the  use  of  the  least 
amount  of  this  material. 

Stove  putty  is  composed  of  finely  divided  graphitic  carbon 
that  is  made  into  a  paste  suitable  for  filling  all  imperfect  joints. 
When  the  putty  hardens  it  withstands  the  heat  to  which  it  is 
subjected,  without  shrinking.  In  the  course  of  time,  however, 
the  putty  may  be  displaced  and  leave  openings  through  which 
the  furnace  gases  may  leak  into  heating  space  and  thus  enter  the 
house.  Leaks  of  the  kind  may  be  stopped  by  renewing  the  putty 
which  may  be  obtained  from  any  dealer  in  stoves. 

Location  of  the  Furnace. — The  location  of  the  furnace  will 
generally  be  governed  by  the  exposure  of  the  house  and  the 
location  of  the  chimney.  In  all  exposed  rooms  on  the  windward 
side  of  the  house  tlie  temperature  will  be  lower  and  the  air  pres- 
sure higher  than  in  other  parts  of  the  house.  The  increase  in 
atmospheric  pressure  makes  it  necessary  to  supply  to  such  rooms 
the  hottest  air  practicable.  The  conducting  pipes,  therefore, 
should  be  most  directly  connected  with  the  furnace  and  with  the 
least  run  of  horizontal  pipe.  The  proper  place  for  the  furnace 
is  as  near  as  possible  the  coldest  place  of  the  house. 

It  is  a  common  practice  to  place  registers  near  the  inner  corner 
of  the  room,  in  order  to  economize  in  conducting  pipe,  in  hori- 


THE  HOT-AIR  FURNACE 


55 


zontal  runs.     A  small  amount  of  economy  in  first  cost  is  thus 
secured  but  the  efficiency  of  the  apparatus  is  sacrificed. 

The  greatest  objection  to  placing  the  registers  and  conducting 
pipes  in  the  outer  walls  of  buildings  is  that  of  loss  of  heat,  due 
to  exposure  to  the  outside  cold  and  the  resulting  loss  in  circula- 
tion. Losses  of  this  kind  may  be  prevented  by  covering  the 
ducts  with  the  necessary  non-conducting  material.  The  regis- 
ters should  occupy  a  place  in  the  room 
nearest  the  entering  cold,  air. 

Flues. — It  is  customary  to  place  the 
conducting  pipes  for  the  first  floor  in 
such  a  way  as  to  use  only  the  shortest 
connections.  The  flues  used  for  the 
second  floor  produce,  as  in  a  chimney, 
a  greater  velocity  of  flow  to  the  air 
and  as  a  consequence  larger  horizontal 
pipes  are  used  at  the  furnace.  All 
horizontal  pipes  should  have  upward 
slant,  as  much  as  the  basement  will 
permit. 

The  velocity  of  the  air  in  the  con- 
ducting flues  will  depend  on  two  fac- 
tors: the  height  of  the  flue,  and  the 
temperature  of  the  air.  To  prevent 
the  loss  of  the  temperature  of  the  air, 

the  flue  should  be  covered  with  at  least      pIG.  46.— Method  of  con- 
two  layers  of  asbestUS  paper  bound  with   ducting  warm  air  from  the  fur- 
iT7   11     a  nace  to  the  registers. 

wire.     Wall   flues  are  commonly  flat- 
tened and  occupy  a  place  in  the  wall  between  the  studding. 
Each  flue  should  have  a  damper  at  the  furnace,  that  will  per- 
mit the  heat  to  be  shut  off  from  any  part  of  the  house. 

Rules  for  proportioning  of  registers  and  conducting  flues  to 
suit  rooms  of  various  sizes  are  entirely  empirical.  The  sizes 
of  registers  and  flues  found  satisfactory  in  practice  is  generally 
a  guide  for  the  designer.  The  following  table  is  taken  from  a 
manufacturer's  catalogue  and  gives  a  list  of  sizes  that  have  proven 
satisfactory  under  a  great  variety  of  conditions  and  may  be 
taken  as  good  practice: 


56 


MECHANICS  OF  THE  HOUSEHOLD 


FIRST  FLOOR 


Sizes  of  registers 

Diameter  of  pipes 

Size  of  rooms 

Height  of  ceilings 

in  inches 

in  inches 

in  feet 

in  feet 

12  by  15 

12 

18  by  20 

11 

10  by  14 

10 

15  by  15 

10 

9  by  12 

9 

14  by  15 

9 

8  by  12 

9 

13  by  13 

9 

SECOND  FLOOR 


10  by  14 

10 

18  by  20 

10 

9  by  12 

9 

16  by  16 

9 

8  by  12 

8 

13  by  13 

8 

8  by  10 

7 

12  by  12 

8 

WARM 
AIR 


WARM 
A,R, 


The  furnace  is  not  only  a  means  of  heating  the  hosne  but  may 

be  a  means  of  ventilation  as 
well;  to  this  end  it  is  desir- 
able to  arrange  the  air  supply 
of  the  furnace  to  connect  with 
the  outside  air.  This  arrange- 
ment assures  a  supply  of 
oxygen  even  though  no  special 
means  is  arranged  for  dis- 
charging the  vitiated  air  from 
the  rooms. 

Combination  Hot-air  and 
Hot- water  Heater. — In  the 
case  of  large  houses  heated 
by  hot  air  it  is  sometimes 
better  to  use  two  or  more 
furnaces  than  to  attempt  to 
carry  the  heat  long  dis- 
tances in  the  customary 
pipes.  Where  heat  is  re- 
quired in  rooms  located  at  a 

distance  more  than  30  feet,  it  is  advisable  to  use  a  combination 
hot-air  and  hot- water  heater,  the'  distant  rooms  being  heated 
by  hot-water  radiators. 

A  furnace  arranged  for  such  a  combination  is  shown  in  Fig.  47. 


FIG  47. — Interior  construction  of  a  com- 
bination hot-water  and  hot-air  furnace. 


THE  HOT-AIR  FURNACE 


57 


This  furnace  contains,  first,  the  essential  features  of  a  hot-air 
furnace;  next,  it  includes  a  hot- water  plant.  The  fire-box  and 
air-heating  surfaces  are  easily  recognized.  The  arrows  show  the 
course  of  the  air  entering  at  the  bottom  of  the  furnace,  which 
after  being  heated  by  passing  over  the  heating  surfaces,  escapes 
at  the  openings  marked  warm  Mir,  to  the  distributing  pipes. 

Inside  the  air-heating  surfaces  are  three  hollow  cast-iron  pieces 
W,  that  form  a  part  of  the  walls  of  the  fire-box.  These  pieces, 
with  their  connecting  pipes,  form  the  water-heating  part  of  %he 


FIG.  48. — The  hot-air  furnace  as  it  appears  in  the  house. 


furnace,  which  supplies  the  hot  water  for  the  radiators.  The 
pieces  W,  with  the  connecting  pipes  and  radiators,  form  an  in- 
dependent heating  plant,  with  a  fire-box  in  common  with  the' 
hot-air  furnace. 

The  returning  water  from  the  radiators  enters  the  heating 
surfaces  W,  through  the  pipe  marked  return  pipe.  The  heated 
water  is  discharged  from  the  heaters  into  that  marked  flow  pipe 
which  conducts  it  to  the  radiators.  Such  a  furnace  is,  therefore, 
two  independent  systems,  one  for  hot  air  and  the  other  for  hot 
water,  but  with  a  single  fire-box.  This  furnace,  like  the  simple 
hot-air  furnace,  is  rated,  first  in  the  amount  of  space  it  will  heat 


58 


MECHANICS  OF  THE  HOUSEHOLD 


with  hot  air  and  in  addition,  by  the  number  of  square  feet  of 
hot-water  radiating  surface  that  will  be  kept  hot  by  the  hot- 
water  heater. 

In  Fig.  48  is  shown  the  location  of  the  furnace  in  a  cottage 
with  the  conducting  pipes  to  the  various  rooms.-  The  registers  in 
the  first  floor  are  generally  set  in  the  floor  but  if  desired  they 
may  be  placed  in  the  walls.  Those  on  the  second  floor  are  placed 
in  the  walls  because  of  convenience.  The  conducting  pipes  pass 
through  the  partitions  between  the  studding. 


FIG.  49. — Details  of  air  ducts  and  damper  regulator  used  with  the  hot-air  furnace . 

In  all  well-arranged  hot-air  heating  plants  provision  is  made  so 
that  the  air  for  heating  may  be  taken  from  the  outside.  It  does 
not  follow  that  the  supply  ojLfresh  air  should  always  come  from 
outdoors;  there  are  times  during  extremely  cold  weather,  ac- 
companied by  high  winds,  when  ventilation  is  ample  without  the 
outside  source  of  supply.  Since  it  is  never  desirable  to  take  the 
air  supply  from  the  basement,  such  an  arrangement  as  is  shown 
in  Fig.  49,  or  a  modification  of  the  same  plan  is  commonly  em- 
ployed. The  duct  A  from  the  outside  and  B  from  the  rooms 
above  connect  with  the  air  supply  for  the  furnaces.  A  damper  C 
arranged  to  move  on  a  hinge,  is  so  placed  as  to  admit  the  air  from 
either  source  as  desired.  The  damper  may  be  placed  so  as  to  take 
part  or  all  of  the  air  from  the  outside  by  adjusting  the  handle  at 
the  proper  place. 


CHAPTER  It 
TEMPERATURE  REG¥LATI€)N 

The  method  used  for  regulating  the  temperature  of  a  house 
will  depend  on  its  size,  the  conditions  under  which  it  is  to  be  used 
and  the  method  of  heating.  In  small  houses  the  temperature 
may  be  satisfactorily  governed  entirely  by  hand,  that  is,  the 
furnace  drafts  may  be  changed  by  hand  to  suit  the  varying 
conditions  of  temperature.  A  more  satisfactory  method  is  that 
of  thermostatic  regulation,  in  which  a  thermostatic  governor  and 
a  motor  automatically  control  .the  furnace  dampers  so  as  to  keep 
a  constant  temperature  at  one  point,  generally  the  living  room. 
Where  hot-water  or  steam  heating  plants  are  used,  another  device 
is  frequently  employed  to  keep  the  temperature  of  the  heat  supply 
at  a  constant  degree.  This  is  known  as  the  automatic  damper 
regulator.  The  damper  regulator  is  one  of  the  boiler  accessories 
which  so  governs  the  drafts  of  the  furnace  as  to  keep  a  constant 
water  temperature  in  the  hot-water  heater  or  a  constant  steam 
pressure  in  the  steam  boiler. 

In  some  cases  both  the  damper  regulator  and  the  thermostat 
are  used  as  a  more  complete  means  of  temperature  control. 

.Hand  Regulation. — As  a  means  of  changing  the  dampers  of  the 
furnace  from  the  floor  above,  to  suit  the  prevailing  conditions, 
the  arrangement  shown  in  Fig.  49  does  away  with  the  necessity 
of  a  journey  to  the  basement,  to  remedy  each  change  of 
temperature. 

A  plate  is  fastened  to  the  wall  at  any  convenient  place^  to 
which  the  end  of  a  chain  is  attached  as  shown  in  trie  figure. 
'This  connects  with  a  second  chain,  the  ends  of  which  are  fastened, 
one  to  the  direct  draft  or  ash-pit  damper  F,  and  the  other  to  the 
check  draft  E,  in  the  chimney.  As  the  furnace  appears  in  the 
drawing,  the  direct  draft  is  closed  and  the  check  draft  is  open. 
By  changing  the  ring  from  G  to  H,  the  movement  of  the  chain 
opens  F,  and  closes  E,  admitting  air  to  the  furnace.  When  the 

59 


60 


MECHANICS  OF  THE  HOUSEHOLD 


temperature  of  the  room  is  raised  sufficiently,  the  drafts  are  re- 
stored to  their  original  position  by  replacing  the  ring  at  G. 
Sometimes  one  or  more  intermediate  points  are  made  on  the  plate 
between  G  and  H,  which  permits  both  drafts  to  be  kept  partly 
open  and  fewer  changes  are  required  to  keep  the  temperature 
approximately  normal. 

Damper  Regulator  for  Steam  Boiler. — The  damper_regulator 
used  on  a  steam  boiler  is  a  simple  device  that  automatically 
controls  the  draft  dampers  by  reason  of  the  changing  pressures 
of  the  steam.  The  object  of  the  damper  regulator  is  to  prevent 
the  generation  of  steam  in  the  boiler  beyond  a  certain  pressure 
at  which  the  valve  is  set.  This  point  is  usually  3  or  4  pounds 


FIG.  50. — Cross-section  of  damper 
regulator  for  steam  boiler. 


FIG.  51. — Steam  boiler  for  house 
heating,  with  the  damper  regulator, 
in  place,  attached  to  the  dampers. 


below  the  pressure  at  which  the  safety  valve  would  act.  If  in. 
proper  working  order  the  damper  regulator  will  so  control  the 
dampers  that  the  boiler  will  always  contain  a  supply  of  steam, 
but  the  pressure  will  not  reach  a  point  requiring  the  action  of  the 
safety  valve.  Fig.  51  illustrates  its  connections  with  the  furnace 
dampers.  In  Fig.  18  the  regulator  appears  at  D.  In  external 
appearance  and  in  operation  of  the  dampers,  it  is  the  same  as  the 
regulator  for  a  hot-water  boiler  but  its  internal  construction  is 
simpler.  Fig.  50  shows  its  construction:  It  is  attached  to  the 
steam  space  of  the  boiler  at  E.  The  steam  pressure  acts  directly 
on  the  flexible  metallic  diaphragm.  B.  As  the  pressure  of  the 


TEMPERATURE  REGULATION  61 

steam  approaches  the  desired  amount  the  diaphragm  is  caised 
and  with  it  the  lever  V.  A  chain  D,  attached  to  the  end  of  the 
lever,  opens  the  check  draft,  and  another  at  C  closes  the  draft 
damper.  When  the  steam  pressure  falls,  the  diaphragm  lowers 
the  lever  and  the  dampers  are  restored  to  their  original  position. 
The  same  movements  are  repeated  with  each  rise  and  fall  of  the 
steam  pressure. 

Damper  Regulators  for  Hot-water  Furnaces.— The  damper 
regulator  for  a  hot-water  boiler  automatically  controls  the 
dampers  of  the  furnace  so  as  to  keep  the  water  of  the  boiler 
approximately  at  a  constant  temperature.  The  regulator  is 
shown  in  Fig.  52.  The  ends  of  the  lever  are  connected  to  the 
direct-draft  and  check-draft  dampers,  as  in  the  case  of  the 


a 
FIG.  52. — Damper  regulator  for  hot-water  boiler. 

damper  regulator  for  the  steam  plant.  A  cross-section  of  the 
working  parts  shows  the  details  of  construction.  The  lever  d  is 
operated  by  a  diaphragm  g,  which  tightly  covers  a  brass  bowl, 
containing  a  mixture  of  alcohol  and  water,  of  such  proportions 
as  will  produce  a  vapor  pressure  at  the  desired  temperature, 
say  200°.  The  hot  water  from  the  boiler  passes  through  the 
valve,  entering  at  a  and  leaving  at  b.  When  the  water  reaches 
the  desired  temperature,  the  contained  liquid  vaporizes  and  a 
pressure  is  produced  that  is  sufficient  to  lift  the  diaphragm  and 
the  lever.  The  chain  attached  to  the  right-hand  end  closes  the 
direct-draft  damper;  at  the  same  time  the  other  end  of  the  lever 
opens  the  check  draft,  and  the  supply  of  air  to  the  furnace  fire 
is  entirely  cut  off.  As  soon  as  the  water  has  cooled  sufficiently, 


62  MECHANICS  OF  THE  HOUSEHOLD 

the  vapor  pressure  in  the  bowl  is  reduced,  allowing  the  weight 
W  to  depress  the  diaphragm  and  the  lever  is  restored  to  its  first 
position.  The  weight  W  is  for  adjusting  the  valve  to  the  desired 
temperature.  The  plug  /  tightly  closes  the  orifice  through  which 
the  liquid  is  introduced  into  the  bowl. 

The  object  of  the  damper  regulator  on  a  hot- water  boiler  is 
to  govern  the  fire  of  the  furnace  so  as  to  keep  the  water  in  the 
boiler  at  the  desired  temperature.  In  case  there  is  a  demand 
for  heat  at  any  part  of  the  house,  a  supply  of  hot  water  will 
always  be  on  hand.  It  has  nothing  to  do  with  the  regulation 
of  the  temperature  of  the  house.  The  control  of  the  house 
temperature  is  the  office  of  the  thermostat. 

The  thermostat  is  a  mechanical  device  for  automatically  regu- 
lating temperature.  It  may  be  arranged  to  operate  the  valve 
of  a  single  radiator  or  register  and  so  control  the  temperature  of 
a  room,  or  as  commonly  used  in  the  average  dwelling,  the  con- 
troller may  be  placed  to  govern  the  temperature  of  the  living 
room  and  in  so  doing  keep  the  furnace  in  condition  to  satis- 
factorily heat  the  remainder  of  the  house. 

Thermostats  are  made  in  a  variety  of  forms  by  different 
manufacturers  but  they  may  be  divided  into  two  general  classes : 
the  electric,  and  the  pneumatic  types.  The  electric  thermostat 
depends  on  an  electric  current  as  a  means  of  controlling  the 
action  of  the  motor  which  in  turn  operates  the  furnace  dampers 
so  as  to  maintain  a  constant  heat  supply.  The  pneumatic 
thermostat  regulates  the  supply  of  heat  by  means  of  pneumatic 
valves.  It  will  be  considered  later  in  discussing  mechanical 
ventilation.  This  type  of  temperature  regulation  is  particularly 
adapted  to  large  buildings. 

Fig.  53  illustrates  one  style  of  electric  thermostat  that  is  very 
generally  used  for  temperature  regulation  in  the  average  dwelling. 
It  consists  of  three  distinct  parts — the  controller,  the  electric  bat- 
tery and  the  motor.  In  the  drawing  the  motor  is  shown  connected 
with  a  steam  valve,  such  as  may  be  used  for  furnishing  steam 
for  a  series  of  radiators.  It  may  with  equal  facility  be  attached 
to  the  dampers  of  a  furnace  or  other  heating  apparatus. 

The  controller  occupies  a  place  on  the  wall  of  the  room  to  be 
heated  and  makes  electric  connections  between  the  battery  and 
the  motor.  Whenever  the  temperature  varies  from  the  required 


TEMPERATURE  REGULATION  63 

degree,  a  change  of  electric  contact  in  the  controller  starts  the 
motor,  and  the  radiator  valve  or  the  furnace  drafts  are  opened 
or  closed  as  occasion  requires. 

The  controller  appears  in  Fig.  54  as  commonly  seen  in  use. 
The  upper  part  carries  a  thermometer  and  the  pointer  A  indicates 
the  temperature  to  be  maintained  in  the  room.  The  middle 
division  indicates  70°F.  Each  division  to  the  right  of  the  middle 
point  raises  the  temperature  5°.  Each  division  to  the  left  lowers 
the  temperature  a  like  amount. 

In  addition  to  the  ordinary  type  this  controller  is  furnished 
with  a  time  attachment  by  means  of  which  the  controller  may 
permit  the  temperature  of  the  room  to  fall  to  any  desired  degree 
at  night  and  raise  it  again  in  the  morning  at  the  time  for  which 
it  is  set. 

This  is  accomplished  by  a  little  alarm  clock  shown  at  the 
bottom  of  the  controller  in  Fig.  54.  The  indicator  B  is  arranged 
to  correspond  with  the  indicator  A ;  the  middle  point  representing 
70°F.  To  set  the  time  attachment,  the  alarm  is  wound  and  set 
as  in  any  alarm  clock,  %  hour  earlier  than  the  desired  time  for 
rising.  The  indicator  B  is  set  for  the  day  temperature  and  A  is 
set  for  the  temperature  desired  during  the  night.  At  the 
appointed  time  the  alarm  moves  the  indicator  A  to  the  desired 
point  for  the  day  and  the  controller  raises  the  temperature 
accordingly. 

Fig.  55  shows  the  mechanism  that  is  exposed  to  view  when  the 
cover  of  the  controller  is  removed.  The  bent  strip  C  is  the  part 
that  is  influenced  by  the  change  of  temperature.  It  is  made  of 
two  thin  strips  of  metal,  one  of  brass  and  the  other  of  steel.  The 
two  strips  are  soldered  firmly  together.  Any  change  in  tempera- 
ture will  affect  the  strip  and  cause  it  to  bend  and  touch  the 
.contact  point — K  or  J.  The  bending  of  the  strip  is  due  to 
the  unequal  expansion  of  the  brass  and  steel  due  to  the 
change  of  temperature.  Brass  expands  2.4  times  as  much  as 
steel  with  the  same  change  of  temperature.  The  amount  of 
bending  is  sufficient  to  make  an  appreciable  movement  in  a  small 
fraction  of  a  degree  change.  The  brass  part  of  C  is  on  the  left 
and  since  it  expands  the  greater  amount,  a  rising  temperature 
causes  C  to  come  into  contact  with  the  point  J.  When  this 
happens  the  motor  is  started  and  makes  one-half  cycle.  In  so 


64  MECHANICS  OF  THE  HOUSEHOLD 

doing  it  shuts  off  the  air  supply  of  the  furnace,  opens  the  check 
draft  and  at  the  same  time  the  motor  changes  the  electric  contact 
from  J  to  K.  When  the  temperature  begins  to  fall,  the  brass  con- 
tracts in  the  same  ratio  to  the  steel  as  it  expands  during  the 
rising  temperature  and  as  a  consequence  the  bar  bends  to  the 
left.  When  the  strip  touches  the  point  K  the  motor  again  makes 
one-half  circle,  admitting  air  once  more  to  the  furnace,  closes 
the  check  draft  and  shifts  the  electric  contact  back  to  K.  When 
properly  started  the  thermostat  will  regulate  the  temperature 
within  a  degree  of  temperature. 

The  Thermostat  Motor. — The  thermostat  motor  automatically 
opens  and  closes  the  furnace  dampers  or  the  valve  that  admits 
steam  to  the  radiators  as  heat  is  demanded  by  the  controller. 

The  motor,  as  shown  in  Fig  53,  consists  of  a  system  of  gears 
and  a  brake  S,  which  regulates  the  speed,  a  cam  M,  and  armature 
7,  for  starting  and  stopping  the  motor,  and  the  electromagnet]7f-7f 
which  operates  the  bar  7.  Two  lever  arms  L,  one  in  front  and 
the  other  at  the  back  of  the  motor  furnish  means  for  attachment 
to  the  valve  or  furnace  dampers.  An  emergency  switch  at  D 
is  shown  in  detail  in  Fig.  56.  The  battery  B  furnishes  the  cur- 
rent which  energizes  the  magnets  and  an  iron  weight  supplies  the 
motive  power  for  the  motor. 

The  description  of  the  operation  of  the  motor  applies  to  the 
steam  valve  shown  in  Pig.  53.  The  same  motor  might  be  used 
for  opening  and  closing  of  the  dampers  of  the  furnace  in  any  kind 
of  heat  supply.  The  method  of  communicating  the  motion  of 
the  motor  arms  to  the  dampers  of  the  furnace  will  be  described 
later.  The  connections  with  the  furnace  drafts  are  shown  in 
Figs.  3,  6,  8,  34,  etc. 

Suppose  that  the  valve  for  admitting  steam  to  the  radiators, 
as  that  in  Fig.  53,  is  closed  and  that  the  temperature  of  the  house 
is  falling.  The  strip  C  of  the  thermostat  controller  is  moving 
toward  J.  When  contact  is  made,  the  current  from  the  battery 
B  energizes  the  magnets  H-H  and  the  bar  7  is  lifted.  As  the 
bar  7  is  raised  the  catch  J  is  released  and  permits  the  motor  to 
start.  The  bar  7  is  held  suspended  by  the  cam  M  until  the  arm 
L  has  made  one-half  revolution,  when  the  lug  K  drops  into  the 
depression  in  the  cam  made  to  receive  it  and  the  catch  /  engages 
with  the  brake  and  stops  the  motor. 


TEMPERATURE  REGULATION 


65 


FIG.  53. — Thermostat  complete  with  the  regulator,  battery  and  motor,  attached 

to  a  steam  supply  valyp. 
5 


MECHANICS  OF  THE  HOUSEHOLD 


During  this  movement  the  arm  L  has  lifted  the  valve  arm  N  and 
the  valve  admits  steam  to  the  radiators,  at  the  same  time  the  con- 
tact M  has  been  shifted  from  the  right-hand  contact  to  the  left, 
and  the  electric  circuit  is  ready  to  be  made  in  the  controller  at  the 
point  K.  When  the  temperature  has  fallen  a  sufficient  amount 
the  controller  bar  C  will  make  contact  at  K 
and  the  motor  will  again  make  a  half  cycle, 
changing  the  valve  back  to  its  original  posi- 
tion. This  process  will  be  kept  up  so  long 
as  the  motor  is  wound  and  there  is  sufficient 
fuel  in  the  furnace  to  raise  the  temperature. 
Fig.  55  shows  the  method  of  connecting  the 
electric  wires  from  the  battery  to  the  con- 
troller. A  three-wire  cable  connects  the 
battery,  and  makes  contacts  as  indicated  at 
H}  K  and  J.  The  wires  are  shown  attached 
to  the  motor  as  in  Fig.  55.  A  wire  is  taken 
from  either  pole  of  the  battery  and  attached 
to  one  of  the  ends  of  the  magnet  coil.  Pass- 
ing through  the  magnet  the  wire  is  attached 
to  the  frame  of  the  motor.  This  makes  the 
cam  M  a  part  of  the  electric  circuit.  The 
other  two  wires  are  attached  to  the  brass 
strips  on  each  side  of  the  arm  L.  The  strips 
are  insulated  from  the  frame.  The  electric 
circuit  through  the  magnet  is  made  alter- 
nately by  contact  with  the  strips  at  right 
and  left  of  the  arm  L. 

In 'Case  the  motor,  through  neglect,  runs 
down,  a  safety  switch  at  D  (Fig.  53)  discon- 
nects the  battery  and  keeps  it  from  being  dis- 
charged. This  switch  is  shown  in  detail  in 
Fig.  56.  When  the  weight  has  reached  its 
limit,  the  piece  C  on  the  chain  comes  into 
contact  with  D  and  lifting  it  out  of  contact,  breaks  the  circuit. 
When  the  motor  is  again  wound,  C  engages  with  E  and  restores 
the  contact.  The  switch  is  so  arranged  that  when  open,  the  valve 
will  always  be  closed. 


FIG.  54. — Thermo- 
static  regulator  with 
clock  attachment  for 
control  of  day  and 
night  temperature. 


TEMPERATURE  REGULATION 


67 


Combined  Thermostat  and  Damper  Regulator. — It  is  evident 
that,  in  heating  a  house  by  steam,  the  damper  regulator  governs 
only  the  steam  pressure  of  the  boiler.  In  the  use  of  a  thermostat 
alone,  the  regulation  is  that  of  the  temperature  of  the  rooms  only, 
and  has  nothing  to  do  with  the  steam  pressure.  As  an  example : 
Suppose  that  in  cold  weather  the  house  is  cold  and  that  the  gage 
of  the  steam  boiler  shows  no  pressure.  The  desire  is  to  get  up 
steam  as  soon  as  possible.  In  so  doing  a  hot  fire  is  made  with  a 
large  amount  of  fuel.  As  soon  as  the  steam  begins  to  form,  the 
pressure  rises  rapidly.  When  the  radiators  have  become  hot  and 
the  steam  is  no  longer  taken  away  as  fast  as  it  is  formed,  the  pres- 


ALARM  SET 
TIME  SET 


ALARM  WIND 


FIG.  54A. — Showing  the  clock 
attachments  to  the  thermostatic 
regulator. 


FIG.  55. — Mecha- 
nism of  the  thermo- 
static regulator. 


sure  of  the  steam  in  the  boiler  keeps  on  rising.  The  thermostat 
will  not  close  the  furnace  dampers  until  the  temperature  of  the 
rooms  is  normal.  This  may  require  so  great  a  length  of  time 
as  to  produce  a  great  excess  of  steam  that  cannot  be  used  at  the 
time  and  the  pressure  will  be  relieved  by  the  safety  valve.  This 
may  not  be  dangerous  but  it  is  disagreeable.  To  prevent  the 
safety  valve  from  blowing  except  in  case  of  emergency,  a  com- 
bined thermostat  and  draft  regulator  is  used.  In  such  a  com- 


68 


MECHANICS  OF  THE  HOUSEHOLD 


bination,  the  draft  regulator  closes  the  draft  as  soon  as  the  pressure 
reaches  the  desired  point,  after  which  the  thermostat  does  the 
regulating  according  to  suit  the  temperature  of  the  house. 

In  Fig.  2  is  shown  such  a  combination  attached  to  a  boiler. 
The  cord  from  the  regulator,  instead  of  extending  directlyJbp  the 
direct-draft  damper,  passes  over  the  pulley  P  and  connects  to  the 
thermostat  cord.  The  regulator  may  now  close  the  damper  to 
suit  the  steam  pressure,  but  after  ^the 
temperature  in  the  rooms  is  normal,  the 
amount  of  heat  necessary  to  maintain 
the  desired  degree  is  regulated  entirely 
by  the  thermostat  which  opens  and  closes 
the  dampers  regardless  of  the  position 
of  the  damper  regulator. 

If  occasion  should  require  but  a  very 
slight  amount  of  steam  to  keep  the 
house  at  the  desired  temperature,  the 
thermostat  will  govern  the  drafts  aright. 
If  the  steam  pressure  is  in  danger  of  be- 
coming excessive,  the  damper  regulator 
will  govern  the  drafts. 

Thermostat-motor  Connections.  —  The 
arrangement  of  cords  and  pulleys  used/ 
for  attaching  the  thermostat  motor  to 
the  furnace  dampers  will  depend  very 
much  on  local  conditions.  The  motor 

can  be  Placed  in  ***  convenient  position 

tery  circuit  when  the  ther-  so  that  the  connecting  cords  will  act 
most  directly.  The  .motor  opens  and 
closes  the  direct  draft  and  check  draft 
in  accordance  with  the  demand  for  heat.  The  connections  for 
all  kinds  of  furnaces  are  made  in  much  the  same  manner.  The 
pulleys  supplied  with  the  motor  are  placed  to  work  as  freely,  and 
the  cords  to  pull  as  directly  as  possible. 

In  Fig.  57  the  motor  is  connected  with  a  hot-air  furnace.  The 
cord  D  is  attached  to  the  front  arm  of  the  motor  and  connects 
with  the  direct-draft  damper  F.  The  cord  C  connects  the  rear 
arm  of  the  motor  with  the  check-draft  damper  at  E.  In  the 
position  of  the  dampers  shown,  the  direct-draft  damper  is  closed 


Caches  itTiimitr   weight> 


TEMPERATURE  REGULATION 


69 


and  the  air  is  entering  the  chimney  through  the  check  draft  E. 
While  this  damper  is  open  there  is  very  little  induced  draft  to 
supply  the  fire  with  air  that  might  leak  through  the  crevices 
around  the  ash-pit  door,  but  the  gases  from  the  furnace  are 
completely  carried  away  to  the  chimney  by  the  air  entering  at  E. 
In  Figs.  3,  6,  8,  34,  etc.,  the  same  motor  is  connected  with  the 
furnaces  of  various  other  systems  of  heating.  The  object  is  the 


FIG.  57. — Thermostat  motor  connected  with  the  dampers  of  a  hot-air  furnace. 

same  in  all;  when  less  heat  is  required,  the  air  supply  is  cut  off 
and  the  furnace  fire  subsides;  when  more  heat  is  demanded  the  air 
is  again  admitted  to  produce  greater  combustion.  The  check 
draft  is  an  important  feature  as  it  checks  the  flow  of  air  through 
the  furnace  regardless  of  the  position  of  the  direct-draft  damper. 
Even  should  the  direct  draft  be  left  open,  the  check  draft  when 
open  would  destroy  in  a  great  measure  the  supply  of  air  entering 
the  furnace. 


CHAPTER  V 
MANAGEMENT  OF  HEATING  PLANTS 

The  following  instructions  on  the  care  and  management  of 
steam  and  hot-water  heating  plants  is  printed  with  permission 
of  the  American  Radiator  Co.  They  were  prepared  as  a  guide 
to  the  successful  operation  of  the  Ideal  heating  plants  but 
apply  with  equal  force  to  other  plants  of  a  similar  character. 

General  Advice. — No  set  rules  can  be  given  for  caring  for 
every  boiler  alike — chimney  flues  are  not  alike — some  have  strong 
draft,  some  are  average  and  some  are  weak.  There  is  much  more 
difference  in  the  heat-making  qualities  of  coal  than  is  commonly 
known,  and  it  is  important  that  the  right  size  coal  for  the  draft 
be  used.  These  rules  apply  to  most  all  fuels.  A  little  trying  of 
this  way  or  that  way  of  leaving  the  dampers  (when  regulators  are 
not  used)  often  discovers  the  better  way.  It  is  well  to  vary  from 
the  rules  a  little  if  any  of  them  do  not  seem  to  bring  about  the 
best  results. 

With  good,  average  chimney  flue  draft  and  the  right  kind  of 
fuel,  these  rules  will  govern  the  large  majority  of  cases. 

The  Economy  of  Good  Draft. — In  many  cases  a  boiler  with 
sluggish  draft  will  burn  more  coal  than  a  boiler  with  good  draft. 
In  the  first  case  the  fuel  may  be  said  to  "rot" — in  lacking  air 
supply  the  gases  pass  off  unburned.  The  "nagging"  which  a 
boiler  has  to  take  under  these  conditions  increases  the  waste  of 
fuel.  A  boiler  under  sharp,  strong  draft  maintains  a  clear  in- 
tense fire  and  burns  the  gases — getting  the  larger  amount  of 
heat  from  the  coal. 

General  Firing  Rules. — 

1.  Put  but  little  coal  on  a  low  fire. 

2.  When  adding  coal  to  the  boiler,  open  the  smoke-pipe  damper  (in- 
side the  smoke  pipe)  and  close  the  cold-air  check  damper.     This  will 
make  a  draft  through  the  feed  doorway  inward  and  prevent  the  escape 
of  dust  or  gas  into  the  cellar  when  the  feed  door  is  open  to  take  fuel. 
Put  these  parts  back  to  their  regular  places  after  feeding. 

70 


MANAGEMENT  OF  HEATING  PLANTS 


71 


3.  When  it  can  be  done,  in  feeding  a  large  amount  of  coal  (as  for 
night)  leave  a  part  of  the  fire  or  flame  exposed,  so  that  the  gases  may 
be  burned  as  they  arise. 

4.  When  a  regulator  is  not  used,  learn  to  use  the  dampers  correctly 
and  according  to  the  force  of  the  chimney  draft.    Learn  to  use  cold-air 
check  damper.     Often,  when  closing,  the  ash-pit  draft  damper  does 
not  check  the  fire  enough;  opening  the  cold-air  check  damper  will 


FIG.  57a. — Indicates  the  general  condition  of  the  furnace  fire  during  very  cold 
weather.  The  fuel  should  fill  the  fire-pot  to  C.  The  ashes  should  not  be  allowed 
to  accumulate  beyond  B,  on  the  gri^e.  There  should  be  no  more  ashes  than 
appear  at  H,  in  the  ashpit. 

check  it  about  right.     Increasing  or  lessening  the  pressure  of  a  steam 
boiler  must  be  done  by  changing  the  weight  on  the  regulator  bar. 

5.  Carry  a  deep  fire  or  a  high  fire;  let  the  live  coals  come  up  to  the 
feed  door — even  in  mild   weather  when  from  4  to  6  inches  of  ashes 
stand  on  the  grate. 

6.  In  severe  weather  give  the  heater  the  most  careful  attention  the 
last  thing  at  night. 


72  MECHANICS  OF  THE  HOUSEHOLD 

7.  Do  not  overshake  or  poke  the  fire  in  mild  weather;  once  in  a  while 
shake  enough  to  give  place  for  a  little  more  fuel. 

8.  Do  not  let  ashes  bank  up  under  the  grate  in  ash-pit.     Grate  bars 
are  very  hardy,  but  it  is  possible  to  warp  them  with  carelessness.     Tak- 
ing up  the  ashes  once  a  day  is  the  best  rule,  even  if  but  little  has  fallen 
into  the  pit. 

9.  Keep  the  boiler  surfaces  and  flues  clean;  a  crust  of  soot  Y±  inch 
in  thickness  causes  the  boiler  to  require  half  as  much  more  fuel  than 
when  the  surfaces  are  clean. 

10.  If  convenient,  have  a  water  hose  to  spray  the  ashes  when  cleaning 
out  the  pit. 

1 1 .  Attend  the  boiler  from  two  to  four  times  per  day.     In  mild  weather, 
running  with  a  checked  fire,  morning  and  night  is  usually  often  enough. 
In  severe  weather,  once  in  early  morning,  again  at  mid-day,  again  at 
five  or  six  o'clock  and  finally  thorough  attention  at  from  nine  to  eleven 
o'clock  in  the  evening. 

12.  If,  through  burning  poor  coal,  the  fire  pot  gets  full  of  ashes,  or 
slate  and  clinkers  massed  together,  the  quickest  way  to  get  a  good 
active  fire  is  to  dump  the  grate  and  then  build  a  new  fire — from  the 
kindling  up. 

13.  If  a  hard  clinker  lodges  between  the  grate  bars,  do  not  force  the 
shaking,  but  first  dislodge  the  mass  with  a  poker  or  slicing  bar.     Then 
the  grate  will  operate  without  damage. 

Weather  and  Time  of  Day. — In  severe  weather  keep  the  fire 
pot  full  of  coal,  and  run  the  heater  by  the  dampers  or  regulator 
(if  one  is  used).  Thoroughly  clean  the  grate  twice  a  day.  Let 
the  top  of  the  fire  in  front  be  level  with  the  feed  door  sill.  Bank 
up  the  coal  higher  to  the  rear. 

In  moderate  weather  there  should  be  from  2  to  6  inches  of  ashes 
between  the  live  coal  and  the  grate.  As  the  weather  grows 
colder  keep  the  grate  and  the  fire  pot  a  little  cleaner — sometimes 
it  helps  to  run  the  poker  or  slicing  bar  over  it  through  the  clinker 
door.  With  some  fuels  this  is  never  necessary. 

Night  Firing. — In  very  cold  weather,  when  the  house  should  be 
kept  warm  all  night,  clean  the  grate  well  at  a  late  hour — the 
last  thing.  Clear  the  bottom  of  the  fire  pot  of  all  ashes-and  clink- 
ers so  that  the  grate  is  covered  with  clear-burning,  red-hot  coals, 
then  fill  the  pot  full  of  fuel.  If  possible,  leave  some  of  the  flame 
exposed  to  burn  the  gases.  Leave  the  drafts  on  long  enough  to 
burn  off  some  of  the  gas,  then  check  the  heater  for  the  night. 


MANAGEMENT  OF  HEATING  PLANTS  73 

Thus  there  is  plenty  of  coal  to  barn  during  the  night  and  some  on 
which  to  commence  early  in  the  morning.  Some  drafts  do  not 
make  it  necessary  to  leave  the  dampers  on  to  burn  off  the  gas 
after  feeding. 

With  the  ash-pit  draft  damper  closed  and  the  cold-air  check 
damper  open  at  night,  but  part  of  the  coal  is  burned  and  there  is 
much  of  it  not  burned  in  the  morning.  So,  by  reversing  the 
dampers  in  the  early  morning  the  fire  starts  up  quickly  and  often 
the  house  may  be  well  warmed  before  any  coal  is  put  into  the 
fire  pot. 

Some  boilers  are  run  the  other  way — a  very  poor  way.  If  the 
grate  is  cleared  off  in  very  cold  weather  and  coal  added  at  five 
or  six  o'clock  in  the  afternoon,  by  eleven  o'clock  at  night  nearly 
one-half  of  the  coal  is  burned  and  the  grate  is  covered  over  with 
a  mass  of  ashes  and  clinkers.  With  little  coal  remaining,  to 
shake  the  grate  will  quite  likely  put  out  the  remaining  fire;  to 
put  fresh  coal  on  a  low  fire"  reduces  further  its  declining  tem- 
perature. The  result  is  a  cold  house  that  will  grow  colder  until 
a  new  fire  is  started. 

Often  in  cold  weather  with  this  poor  way  of  night  firing,  it 
takes  one  or  more  hours  of  forced  firing  to  warm  the  house  in  the 
morning,  and  all  the  coal  saved  the  night  before  is  more  than 
used  to  get  the  house  or  building  " heated  up" — while  the  people 
who  should  be  comfortable  have  to  get  up,  bathe  and  take  break- 
fast in  chilly  rooms.  At  no  time  in  the  day  is  heat  more  wanted 
than  about  the  time  of  getting  up  and  starting  the  day.  A 
fire  well  cared  for  late  in  the  evening  makes  a  warm  house 
all  night.  And  so  it  follows  that  it  is  much  easier  to  add  a 
little  more  heat  in  the  morning.  And  surely  less  coal  is  burned, 
for  the  forcing  of  a  fire  part  of  the  time  often  overheats,  and 
wastes  coal. 

First-day  Firing. — In  the  morning  of  moderate  winter  weather, 
with  the  ash-pit  draft  damper  open,  before  adding  any  coal  allow 
the  fire  to  brighten  up  if  it  seems  to  be  low ;  then  (for  such  condi- 
tions) spread  over  a  thin  layer  of  fresh  coal  and  set  the  drafts 
for  a  brisk  fire.  After  the  new  fire  is  well  started  add  as  much 
coal  as  may  be  necessary  to  last  until  next  firing.  Do  not  shake 
much  if  any — just  enough  to  give  space  for  more  coal.  Then  by 
setting  the  regulator  (if  one  is  used),  or,  by  closing  the  ash-pit 


74  MECHANICS  OF  THE  HOUSEHOLD 

draft  damper  and  opening  the  cold-air  check  damper  a  little, 
the  boiler  should  keep  up  its  work  until  the  next  firing  time. 

In  severe  weather,  if  the  boiler  has  been  attended  to  at  night  as 
directed  in  the  section  on  " night  firing/'  the  drafts  can  be  turned 
on  and  the  boiler  run  for  half  an  hour  before  adding  coal.  Or,  if 
more  convenient  to  give  it  immediate  attention,  the  grate  can  be 
thoroughly  shaken  and  enough  coal  added  to  last  until  mid-day. 
Often  the  cold-air  check  damper  will  need  to  be  entirely  closed 
and  the  ash-pit  draft  damper  partly  open  if  the  heater  is  a  water 
boiler.  If  a  steam  boiler,  the  regulator  should  then  be  set  to 
maintain  the  number  of  pounds  of  pressure  wanted  and  so  left. 

Other-day  Firing. — In  severe  weather  more  coal  should  be 
added  about  noon,  sometimes  the  draft  may  be  left  on  for  a  few 
minutes  and  then  checked.  And  in  such  weather  it  is  often  well 
to  give  the  boiler  further  attention  at  five  or  six  o'clock.  In 
severest  weather  the  boiler  should  not  be  attended  more  than 
four  times  a  day;  and  generally  not  less  than  three  times. 

Often  much  coal  is  wasted  by  "nagging"  the  fire — poking, 
shaking  and  feeding  it  until  it  becomes  " dyspeptic."  A  sure 
cure  is  a  little  common  sense  in  regular  feeding,  etc. 

Economy  and  Fuels. — In  running  many  boilers  for  moderate 
weather  better  results  follow  if  the  grate  is  not  shaken  too  much  or 
too  often.  Sometimes  in  moderate  weather  a  body  of  ashes  on 
the  grate  checks  the  fire  and  there  is  enough  heat  without  a 
useless  burning  of  fuel.  Many  houses  are  overheated  in  moderate 
weather  and  too  much  coal  burned  by  running  the  boiler  as  for 
zero  weather. 

So  we  repeat — it  is  not  wise  to  overshake  or  overfeed  a  boiler  in 
moderate  weather.  The  fire  should  be  in  such  shape  that  if  a 
change  comes  at  night  there  is  a  basis  for  a  good  fire  to  start  on. 
When  the  grate  is  shaken  but  once  during  the  24  hours  (during 
moderate  weather)  late  at  night  is  the  best  time. 

When  one  stops  to  think  that  heating  is  needed  during  about 
7  months  out  of  the  year,  and  that  a  greater  portion  of  this  time  is 
usually  moderate  weather  when  a  very  little  heat  is  needed,  it 
must  be  seen  that  the  science  of  running  the  heater  to  save  coal 
is  to  apply  common  sense  rules  of  limiting  the  feeding  and  the 
attention  in  such  periods.  In  severe  weather  we  believe  in  giving 
the  boiler  a  liberal  quantity  of  fuel  regularly  and  at  the  right 


MANAGEMENT  OF  HEATING  PLANTS  75 

time.  The  time  to  save  coal  is  when  there  is  no  need  for  burning 
it.  This  is  where  a  great  many  people  make  errors  in  running 
the  boiler — in  forgetting  to  "let  up"  on  the  shaking  and  feeding 
in  moderate  weather. 

With  some  drafts  and  for  boilers  using  hard  coal  or  coke,  good 
economical  results  often  are  secured  by  opening  the  feed  door  a 
little  when  it  is  desired  to  check  the  fire  in  moderate  weather. 
This  depends  on  the  draft. 

For  Burning  Soft  Coal. — Some  types  of  boilers  are  made  to 
burn  soft  coal  with  economy,  with  least  work.  Some  types  are 
made  specially  to  burn  the  meaner  grades  of  soft  coal.  Firing 
to  prevent  smoke  is  a  source  of  economy  and  these  ways  of  run- 
ning should  be  followed — specially  with  large  sectional  boilers. 

There  are  two  types  of  soft  coal,  viz. :  The  free-burning  coal, 
which  breaks  apart  when  burning,  allowing  the  gases  to  freely 
escape;  and  the  fusing-coking  coal,  which,  when  burning,  first 
fuses  into  a  solid  burning  mass  with  a  hard  crust  over  the  top, 
slowly  coking  as  it  burns.  The  latter  kind  is  most  valuable  for 
house-heating  boilers  because  the  gases  are  more  thoroughly 
consumed.  The  fusing-coking. coal  is  worth  about  20  per  cent, 
more  for  this  purpose  than  the  free-burning  coal. 

The  gases  should  be  allowed  to  pass  off  from  the  coal  slowly. 
Leave  air  inlet  on  the  feed  door  open  if  draft  permits.  If  possible, 
use  uniform  sizes  of  coal.  Avoid  using  coal  having  too  much 
dust — the  "  run-of-the-mine  "  may  be  lower  in  price  but  its  heat- 
making  value  is  also  low. 

For  the  purpose  of  slow  burning  of  soft  coal,  it  is  well  in  feed- 
ing at  night  to  let  the  fire  burn  up  freely  so  that  the  coals  are 
very  live  with  heat.  Then  fill  in  enough  coal  to  last  all  night- 
leaving  some  of  the  live  coals  uncovered  if  possible.  With  large 
sectional  boilers  this  exposure  should  be  at  the  rear  of  the  fire  so 
that  the  flame  will  pass  over  the  live  coals.  Thus  the  gases 
coming  off  from  the  fresh  coal  are  burned  and  a  larger  amount 
of  the  full  heat-producing  value  of  soft  coal  is  made  use  of  and 
with  less  smoke. 

After  a  boiler  is  so  fed,  the  dampers  (unless  an  automatic 
regulator  is  used)  should  be  left  about  as  follows : 

Ash-pit  draft  damper  open  a  little  or  closed,  as  draft  may 
require. 


76  MECHANICS  OF  THE  HOUSEHOLD 

Cold-air  check  damper  open  about  one-eighth  to  one-third 
distance  of  the  opening. 

Smoke-pipe  damper  about  one-half  closed. 

A  little  experiment  with  the  draft  will  usually  tell  the  operator 
the  best  way  of  leaving  these  dampers. 

It  will  be  found  in  the  morning  that  the  entire  charge  of  coal 
is  well  burned  or  partly  coked. 

The  coked  fuel,  or  that  which  sticks  together  in  a  mass,  should 
be  broken  up  by  the  poker  and  more  added  generally  as  by  rules 
given  in  other  sections. 

It  must  always  be  remembered  that  the  soft  coals  mined  in 
different  parts  of  the  country  have  widely  varying  heat-mak- 
ing capacities.  To  obtain  satisfactory  results  brands  must  be 
selected  which  have  an  established  reputation  for  excelling  re- 
sults in  small  boilers. 

For  Burning  Coke. — It  is  best  to  keep  the  pot  full  of  fuel- 
keeping  a  large  body  of  coke  under  a  low  fire  rather  than  a  little 
fuel  under  a  strong  fire. 

It  must  be  remembered  that  coke  makes  a  very  "hot  fire" 
because  the  coke  is  free-burning.  Care  should  be  taken  not  to 
leave  drafts  on  too  long  in  boilers  not  having  regulators. 

Coke  burns  best  for  house-heating  purposes  with  less  draft 
than  is  required  for  coal,  therefore  to  keep  a  low  fire  the  ash-pit 
draft  damper  should  be  kept  closed,  and  the  smoke-pipe  damper 
almost  entirely  closed.  The  regulator  (when  used)  can  be  set  to 
keep  the  dampers  about  as  here  advised.  Coke  is  practically 
smokeless  and  its  quick-burning  character  makes  a  cut-off  damper 
in  the  smoke  pipe  (which  will  stay  fixed  as  it  may  be  set)  quite 
necessary. 

It  is  well  to  keep  a  layer  of  ashes  on  the  grates  and  when  shak- 
ing stop  before  red-hot  coals  come  through  the  grate.  The  coke 
then  burns  more  slowly,  which  increases  its  effectiveness. 

With  some  drafts  it  may  be  well  to  "bank  the  fire"  at  night 
with  coke — pea  coal  size.  This  is  a  matter  of  experiment,  and 
depends  on  the  character  of  the  chimney  draft. 

Fire  should  be  tended  regularly — two  times  a  day,  or  four  at 
the  outside. 

With  an  extra  strong  draft,  at  night  the  fuel  should  be  packed 
down  by  tamping  with  the  back  of  a  shovel. 


MANAGEMENT  OF  HEATING  PLANTS  77 

With  ordinary  condition  of  draft,  crushed  coke,  small  egg  size, 
should  be  used. 

Other  Rules  for  Water  Boilers — To  Fill  System. — Open  the 
feed-cock  when  the  heater  is  connected  with  a  city  or  town  water 
supply;  if  not,  fill  by  funnel  at  the  expansion  tank.  Fill  until  the 
gage-glass  on  the  expansion  tank  shows  about  half  full  of  water. 
In  filling  the  system  see  that  all  air  cocks  on  the  radiators  are 
closed.  Then  beginning  with  the  lower  floor,  open  the  air  cocks 
on  each  radiator,  one  at  a  time,  until  each  radiator  is  filled;  then 
close  the  air  cock  and  take  the  next  radiators  on  upper  floors  until 
all  are  filled,  after  which  let  the  water  run  until  it  shows  in  the 
gage-glass  of  the  water  tank.  After  the  water  is  heated  and  in 
circulation,  vent  the  radiators  by  opening  the  air  valves  as  before. 
Then  again  allow  the  water  to  run  into  the  system  until  it  rises 
to  the  proper  level  in  the  expansion  tank  gage-glass. 

Always  keep  the  apparatus  full  of  water  unless  the  building  be 
vacated  during  the  winter  months,  when  the  water  should  be 
drawn  off  to  prevent  freezing.  Never  draw  water  off  with  fire 
in  the  heater. 

To  draw  off  water,  open  the  draw-off  cock  at  the  lowest  point 
in  the  system,  and  then  open  air  cocks  on  all  radiators  as  fast 
as  the  water  lowers  beginning  with  the  highest  radiator. 

Air-vent  Valves  on  Radiators. — In  order  to  secure  the  full 
benefit  of  the  heating  surface  of  a  hot-water  radiator,  the  inside 
of  the  section  must  be  free  of  air.  When  a  radiator  is  ''air- 
bound"  it  means  that  parts  of  the  sections  are  filled  with  air 
in  pockets  which  remain  until  the  air  is  allowed  to  pass  off 
through  the  vent  valve. 

Air  will  gather  from  time  to  time  at  the  highest  points  inside 
4-he  radiators,  especially  in  those  placed  in  the  upper  stories  of  the 
building.  These  air  accumulations  inside  cut  down  the  working 
power  of  a  radiator  exactly  in  proportion  as  they  rob  the  inside 
of  the  casting  of  proper  contact  with  heated  water.  Air  pockets 
not  only  reduce  effective  heating  surface,  but  they  also  prevent 
the  circulation  of  hot  water. 

Therefore,  it  is  well  once  in  a  while  to  take  the  little  key  pro- 
vided by  the  heating  contractor  and  open  the  air  valves  on  radia- 
tors to  allow  the  air  (if  any)  to  escape.  When  a  radiator  does 
not  work  as  well  as  usual,  open  the  air  valves  until  the  water 


78  MECHANICS  OF  THE  HOUSEHOLD 

flows,  which  indicates  that  the  air  has  been  fully  released.     Then 
close  the  valve. 

Valves  on  Cellar  Mains. — If  cut-off  valves  have  been  placed 
on  the  main  and  return  pipes  in  the  cellar,  see  that  the  valves 
on  one  line  of  main  and  return  pipes  (at  least)  are  open  when  the 
boiler  is  under  operation.  Be  sure  that  the  system  is  open  to 
circulate  water  through  the  supply  and  return  pipes  before  build- 
ing a  fire  in  the  boiler. 

End  of  the  Season. — At  the  close  of  the  heating  season  clean 
all  the  fire  and  flue  surfaces  of  the  boiler.  Let  the  water  remain 
in  the  system  during  the  summer  months.  No  bad  results  will 
follow  if  the  system  is  not  refilled  more  often  than  once  in  2  or  3 
years.  But,  generally,  it  is  thought  that  best  results  are  secured 
by  emptying  the  system  once  a  year  (after  fire  is  out)  and  refilling 
with  fresh  water. 

It  is  a  very  good  idea  to  take  down  the  smoke  pipe  in  the  spring, 
thoroughly  clean  and  put  it  back  in  place.  Leave  all  doors  open 
on  the  boiler  in  the  summer  time. 

Other  Rules  for  Steam  Boilers— To  Fill  Boiler.— Open  the 
feed-cock  when  the  heater  is  connected  with  city  or  town  water 
supply;  if  not,  fill  through  the  funnel.  Let  the  water  run  until 
the  gage-glass  shows  about  half  full  of  water. 

In  the  first  filling,  after  the  water  has  boiled,  get  up  a  pressure 
of  at  least  10  pounds,  draw  the  fire  and  blow  off  the  boiler  under 
pressure  through  draw-off  cock  to  remove  oil  and  sediment, 
after  which  refill  with  fresh  water  to  the  water  line.  This  is  best 
done  usually  by  the  steam-fitter. 

The  damper  regulator  will  control  the  pressure  of  steam,  clos- 
ing the  damper  when  the  pressure  is  raised  beyond  the  desired 
point  and  opening  the  damper  when  the  pressure  falls  below  that- 
point.  By  removing  the  weight  on  the  lever,  different  degrees 
of  pressure  can  be  kept  up.  The  regulator  should  be  allowed  to 
control  the  drafts  without  interference. 

Examine  the  water  glass  often  to  see  that  the  water  line  is  at 
the  proper  height.  If  lower  than  normal  open  the  supply  pipe 
until  the  water  runs  in  and  stands  at  the  proper  level.  It  is  best 
when  no  water  stands  in  the  glass,  nor  shows  at  the  bottom  of 
the  try-cock,  to  quickly  dump  the  grate  and  do  not  put  water  into 
the  boiler  again  until  it  is  cooled  off. 


MANAGEMENT  OF  HEATING  PLANTS  79 

If  there  is  one  or  more  shut-off  valves  on  the  main  or  return 
pipes,  before  starting  a  fire  see  that  one  line  of  piping  at  least 
(main  and  return)  is  open  to  circulate  the  steam. 

To  Control  Radiators/ — When  it  is  desired  to  shut  off  steam 
from  any  radiator  (if  the  regular  radiator  valves  are  used),  close 
the  valve  tight,  and  when  it  is  turned  on  see  that  the  valve  is  wide 
open.  A  valve  partly  turned  off  will  cause  the  radiator  to  fill 
with  water.  This  rule  applies  only  to  one-pipe  heating  systems. 

The  Air  Valves. — If  little  keyed  air  valves  (sometimes  called 
"  pet-cocks ")  are  used,  follow  generally  the  same  directions  as 
outlined  for  hot-water  radiators  on  'page  49 — only,  of  course,  in 
releasing  the  air  from  the  radiator  open  the  valve  with  the  key 
provided  and  close  it  just  as  soon  as  the  steam  unmixed  with  air 
comes  through  the  nose  of  the  valve. 

If  " automatic"  air  valves  are  used  they  must  be  carefully 
adjusted  by  the  steam-fitter  and  then  left  to  operate  without 
undue  interference. 

End  of  the  Season. — At  the  close  of  the  heating  season  fill  the 
steam  boiler  with  water  to  the  safety  valve  and  let  it  thus  stand 
through  the  summer. 

Also  thoroughly  clean  all  the  fire  and  flue  surfaces  of  the  boiler 
and  at  the  opening  of  the  next  season  withdraw  the  water  and 
refill  with  fresh  water  to  the  water  line,  starting  the  boiler  as 
before. 

It  is  advisable  to  have  a  competent  steam-fitter  blow  off  the 
boiler  under  pressure  and  thus  give  the  inside  a  thorough  cleaning 
when  the  boiler  is  first  set  up  and  ready  for  fire. 

A  low-pressure  boiler,  using  good  water,  rarely  needs  blowing 
off  after  it  is  once  cleaned  at  time  of  setting  up. 

THE  RIGHT  CHIMNEY  FLUE 

The  area  of  the  flue  should  never  be  less  than  8  inches  in  diame- 
ter if  round,  or  8  by  8  inches  if  square — unless  for  a  very  small 
heating  boiler  or  tank  heater.  Nine  or  10  inches  round,  or  8  by 
12  rectangular  is  a  good  average  size.  The  flue  should  generally 
have  a  little  more  area  than  that  of  the  connecting  smoke  pipes. 

Draft  force  depends  very  much  on  the  height  of  the  flue. 

The  chimney  top  should  run  above  the  highest  part  of  the  roof 


80  MECHANICS  OF  THE  HOUSEHOLD 

and  should  be  so  located  with  reference  to  any  higher  buildings 
nearby  that  the  prevailing  wind  currents  will  not  form  eddies 
which  will  force  the  air  downward  in  the  shaft.  Often  a  shifting 
cowl  which  will  always  turn  the  outlet  away  from  the  source  of 
adverse  currents  will  promote  better  draft. 

The  flue  should  run  as  nearly  straight  up  from  the  base  to  the 
top  outlet  as  possible.  It  should  have  no  other  openings  into  it 
but  the  boiler  smoke  pipe.  Sharp  bends  and  offsets  in  the  flue 
will  often  reduce  the  area  and  choke  the  draft.  The  flue  must  be 
free  of  any  feature  which  prevents  a  free  area  for  the  passage  of 
smoke.  The  outlet  must  not  be  capped  with  any  device  which 
makes  the  area  of  the  outlet  less  than  the  area  of  the  flue. 

The  best  form  of  flue  is  a  round  tile — in  such  there  is  less  fric- 
tion than  in  the  square  form  and  the  spiral  ascent  of  the  draft 
moves  in  the  easiest  and  most  natural  manner. 

If  the  flue  is  made  of  brick  only,  the  stack  should  be  at  least 
two  4-inch  courses  in  thickness. 

If  there  is  a  soot  pocket  in  the  flue  below  the  smoke-pipe  open- 
ing, the  clean-out  door  should  always  be  closed.  If  this  soot 
pocket  has  other  openings  in  it — from  fireplaces  or  other  connec- 
tions— such  arrangements  are  very  liable  to  check  the  draft  and 
prevent  best  action  in  the  boiler. 

The  smoke  pipe  should  not  extend  into  the  flue  beyond  the 
inside  surface  of  the  flue,  otherwise  the  end  of  the  pipe  cuts  down 
the  area  of  the  flue  and  injures  its  drawing  capacity. 

The  inside  of  a  flue  should  be  smooth  (pointed  or  plastered). 
When  the  courses  are  laid  with  the  mortar  bulging  out  from  the 
joints  the  friction  within  the  flue  is  very  much  increased.  Often 
a  troublesome  flue  is  corrected  by  lowering  some  sharp-edged 
weight  by  a  rope  which  should  be  worked  against  the  sides  of  the 
flue  until  the  clogging  is  scraped  off. 

A  new  chimney  when  " green"  will  not  have  a  good  drawing 
capacity.  Short  use  dries  out  the  mortar  and  better  results 
follow. 

"Smokey"  Chimneys. — The  failure  of  draft  in  flues  may  be 
due  to  a  variety  of  causes,  one  of  which  is  illustrated  in  Fig.  576. 
The  short  chimney  on  the  left  side  of  the  roof  shows  the  course 
of  the  wind  as  it  passes  over  the  ridge  of  the  roof  and  why  the 
draft  in  such  a  chimney  is  retarded  whenever  this  condition  exists. 


MANAGEMENT  OF  HEATING  PLANTS 


81 


The  force  of  the  wind,  as  it  comes  into  contact  with  the  roof, 
causes  a  compression  of  the  air  on  the  windward  side  and  a  rarifi- 
cation  on  the  lee  side.  This  inequality  'of  pressure  causes  a 
downward  sweep  of  the  wind  as  indicated  by  the  arrows.  The 
effect  on  the  low  chimney  is  to  retard  the  draft  and  sometimes 
the  pressure  is  great  enough  to  reverse  the  action  of  the  flue  and 


FIG.  576.- — Effect  of  the  wind  in  causing  down  draft  in  low  chimneys. 

force  the  smoke  into  the  house.  The  only  remedy  for  such  a 
condition  is  an  extension  of  the  chimney  that  will  raise  its  top 
above  the  ridge. 

The  same  effect  is  often  produced  by  a  neighboring  build- 
ing or  a  border  of  trees  that  are  higher  than  the  chimney  and 
dense  enough  to  effect  the  wind  pressure. 


CHAPTER  VI 
PLUMBING 

The  term  plumbing  is  usually  understood  to  cover  all  piping 
and  fixtures  that  carry  water  into  the  house  and  remove  the  waste 
material  in  the  form  of  sewage.  It  does  not  include  the  pipes  of 
the  heating  system.  Although  the  work  of  installing  heating 
plants  is  frequently  done  by  plumbers,  pipe  fitting  and  plumbing 
are  two  distinct  trades. 

In  the  process  of  building  a  house  the  rough  plumbing  is  put 
into  place  as  soon  as  the  structure  is  enclosed  and  the  rough 
floors  are  laid.  The  rough  plumbing  includes  the  soil  pipe,  into 
which  the  waste  pipes  from'  the  various  fixtures  empty,  and  those 
pipes  which  must  occupy  a  position  inside  the  partition  walls  and 
beneath  the  floors. 

The  connections  here  described  are  for  a  city  dwelling  and 
apply  to  the  custom  of  local  conditions.  The  same  system 
might  be  used  for  a  country  residence  except  in  regard  to  the 
water  supply  and  method  of  sewage  disposal.  Plants  of  this 
type  are  discussed  in  the  chapter  on  septic  tanks. 

Fig.  58  shows  a  cross-section  of  the  street,  exposing  the  sewer 
S,  the  water  main  W,  and  the  connections  with  the  house.  The 
side  of  the  house  has  been  removed  to  permit  a  view  of  the  water 
and  sewer  pipes,  connecting  with  the  bathroom,  kitchen,  laundry 
and  other  basement  fixtures. 

The  lateral  sewer  or  house  drain,  which  connects  the  house 
with  the  street  sewer  S}  is  provided  with  a  trap  G,  located,  in  this 
case,  just  outside  the  basement  wall.  The  house  drain  is  made 
of  vitrified  tile,  laid  so  as  to  grade  into  the  street  sewer  with  the 
greatest  possible  pitch.  The  sections  are  laid  as  true  as  condi- 
tions will  permit  and  the  joints  are  all  carefully  filled  with  cement 
mortar  to  prevent  leakage.  The  object  of  the  trap  G  is  to  prevent 
sewer  gas  from  entering  the  house  from  the  main  sewer.  The 
trap  prevents  the  gas  from  passing  because  the  water  in  the  bend 

82 


PLUMBING 


83 


of  the  trap  forms  a  water  seal,  beyond  which  the  polluted  air 
from  the  sewer  cannot  travel. 


,*A 


Next  inside  the  trap  is  the  vent  pipe  E,  that  extends  to  the 
surface  of  the  ground.     In  this  case  it  is  just  outside  the  base- 


84 


MECHANICS  OF  THE  HOUSEHOLD 


ment  wall.  The  top  is  covered  with  a  metal  cap.  Another 
arrangement  often  made  to  accomplish  the  same  purpose  is 
shown  in  Figs.  61  and  62,  where  a  piece  of  soil  pipe  in  the  form  of 
a  bend  is  made  to  take  the  place  of  the  cap.  Inside  the  basement 
and  extending  up  through  the  partition  walls  to  the  roof  is  the 
waste  stack  or  soil  pipe  A.  This  pipe  as  is  explained  in  detail 
later,  is  made  of  cast  iron  and  is  put  together  with  calked  lead 
joints.  The  top  of  the  stack  at  the  point  where  it  passes  through 
the  roof  is  shown  in  Fig.  59.  In  extending  through  the  roof  the 
pipe  A  must  make  a  water-tight  joint  to  prevent  water  from 
leaking  through.  This  is  accomplished  by  mea»ns  of  the  metal 

plate  D,  which  is  set  under  the 
shingles  and  the  piece  C,  that  is 
soldered  to  D.  The  joint  between 
C  and  A  is  best  made  with  lead 
the  same  as  the  other  joints  of  the 
stack.  In  the ,  case  of  very  high 


FIG.  59. — Detail  of  soil  pipe 
connection. 


FIG.  60. — Cross-section  of  cellar-drain. 


stacks,  the  b<a£tom  should  be  supported  by  a  pier  or  iron  pipe 
rest.  Besides  being  supported  at  the  base  the  stack  should  be 
secured  to  the  side  walls  or  floor  beams  at  each  floor.  This  is 
to  keep  the  pipe  from  moving  out  of  place  and  the  consequent 
opening  of  joints. 

•All  of 'the  waste  pipes  from  the  bathroom,  kitchen  and  base- 
ment drain  into  the  waste  stack.  The  cellar  drain  for  draining 
the  basement  is  shown  at  T  in  Fig.  58.  It  also  appears  in  detail 
in  Fig.  60.  The  plate  B,  in  the  latter  figure,  is  set  flush  to  the 
surface  of  a  depression  in  the  floor  that  serves  as  a  collecting 
point  for  water.  The  floor  is  constructed  to  drain  toward  this 
point.  The  plate  is  perforated  to  let  the  water  through  and  is 
generally  hinged  so  that  in  case  of  stoppage  the  cover  may  be 
raised.  The  bell-shaped  piece  under  the  cover  surrounds  the 
piece  C,  to  form  a  water  seal  when  the  level  of  the  water  is  at  A. 


PLUMBING 


85 


In  addition  to  this  water  seal  there  is  generally  a  trap  between 
the  drain  and  the  sewer  as  shown  in  the  drawing. 

The  method  of  connecting  the  bathroom  waste  pipes  with  the 
stack  is  shown  in  Fig.  99  and  will  be  described  later.  All  of  the 
sewage  of  the  house  is  emptied  into  the  stack  by  the  most  direct 
route,  and  from  the  stack  it  is  conducted  as  directly  as  possible 
into  the  sewer.  From  the  drawing  it  will  be  seen  that  all  open- 
ings to  the  sewer  are  sealed  in  two  separate  places,  once  at  the 
outlet  to  prevent  the  air  from  the  street  sewer  entering  the  house 
drain  G,  and  again  at  each  opening  to  prevent  escape  of  the  sewer 
gas  from  the  drain  into  the  house. 


Vent 


Trap  Trap 

FIG.  61.  FIG.  62. 

FIG.  61. — House  drain  with,  outside  vent,  and  running  trap  placed  inside  the 
basement  wall. 

FIG.  62. — House  drain  with  outside  vent,  and  running  trap  placed  outside 
the  basement  wall. 

The  openings  at  E  and  A  at  each  end  of  the  stack  permit  a 
constant  circulation  of  air  for  ventilation.  The  length  of  the 
stack  and  its  location  causes  it  to  act  as  a  chimney  and  the 
draught  produced  takes  the  air  in  at  E>  and  discharges  it  at  the 
top.  In  large  houses  there  is  sometimes  added  a  vent  stack  to 
produce  further  ventilation,  but  in  the  average  dwelling  the 
arrangement  here  shown  covers  the  common  practice. 

In  Figs.  61  and  62  are  shown  in  detail  two  methods  of  arranging 
the  sewer  connections  in  the  basement  to  permit  of  the  removal 
of  obstructions  in  case  the  pipes  at  any  time  become  stopped. 
The  trap,  vent,  etc.,  are  easily  recognized.  With  the  arrangement 
as  shown  in  Fig.  62,  th#  clean-out  is  so  placed  as  to  give  access 
to  the  inside  of  the  pipe.  *  Should  an  accumulation  or  obstruction 
of  any  kind  become  lodged  in  the  pipe,  the  stop  in  the  clean-out 


86  MECHANICS  OF  THE  HOUSEHOLD 

is  removed  and  a  flexible  metal  rod  is  used  to  remove  the  stop- 
page. The  trap  outside  the  wall  has  an  opening  through  which 
the  obstruction  may  be  reached  in  case  it  cannot  be  removed 
from  the  first  clean-out.  The  disadvantage  in  usin^  the  out- 
side trap,  as  here  shown,  is  that  it  can  be  reached  only  by 
excavation. 

Fig.  61  shows  another  common  method  of  installation.  Here 
the  trap  is  placed  inside  the  basement  wall.  This  gives  an 
easier  means  of  opening  the  trap  than  Fig.  62  affords  and 
accomplishes  the  same  purpose.  The  connections  with  the 
stack  are  the  same  as  in  Fig.  62.  Obstructions  in  the  sewer  pipe 
are  most  likely  to  become  lodged  in  the  trap  and  for  this  reason 
the  trap  should  occupy  a  position  that  is  reasonably  easy  of 
access. 

The  outside  trap  as  described  above  is  quite  generally  installed 
in  buildings  of  all  kinds,  but  its  use  is  by  no  means  universal.  In 
some  communities  it  is  not  used  at  all,  and  many  plumbers 
consider  it  only  an  added  means  of  causing  stoppage  and  an 
extra  expense  to  install. 

The  object  -of  the  outside  trap  is  to  keep  the  air  of  the  street 
sewer  from  entering  the  house  drain.  It  is  at  once  inferred  that 
the  air  of  the  street  sewer  is  more  dangerous  than  that  of  the 
house  drain.  The  street  sewers,  however,  are  ventilated  at  each 
street  corner  and  at  each  manhole.  There  cannot  then  be  much 
difference  in  the  air  of  the  two  places.  The  traps  on  the  fixtures 
that  prevent  sewer  gas  from  entering  the  house  would  be  just 
as  efficient  if  the  outside  trap  did  not  exist. 

While  the^methods  shown  in  Figs.  61  and  62  are  considered  good 
practice,  there  is  considerable  objection  to  the  vent  being  placed 
near  the  dwelling,  because  of  the  sewer  gas  that  is  forced  out, 
whenever  a  sudden  discharge  of  water  goes  into  the  drain.  Each 
time  a  closet  is  flushed,  a  large  volume  of  water  enters  the  stack 
and  completely  fills  the  pipe.  When  this  occurs,  the  descending 
water  forces  out  the  air  of  the  pipe  ahead  of  it,  and  a  gush  of 
offensive  air  filled  with  sewer  gases  is  forced  out  of  the  vent. 
It  is  evident  that  such  a  vent,  located  near  an  open  window  or 
where  it  will  reach  the  nostrils  of  the  inhabitants  is  a  thing 
not  greatly  to  be  desired. 

Outside  traps  when  placed  near  the  surface  sometimes  freeze. 


PLUMBING 


87 


The  circulation  of  air  through  the  vent  is  occasionally  sufficient  in 
cold  weather  to  freeze  the  water  and  stop  the  trap. 

Water  Supply. — The  water  supply  taken  from  the  street  main 
is  conducted  to  the  house  by  the  pipe  shown  in  Fig.  58,  at  C. 


FIG.  63. — -Corporation  cock  with  lead  connecting  pipe. 

This  pipe  is  generally  of  lead  as  piping  of  that  metal  is  the  most 
durable  for  underground  work.  Iron  used  under  the  same  con- 
ditions will  last  only  a  few  years.  The  connection  is  made  with 
the  water  main  by  use  of  a  corporation  cock. 
This  is  a  special  style  of  cock  that  is  shown 
in  Fig.  63.  In  the  figure  the  cock  is  connected 
with  a  short  piece  of  lead  pipe  that  is  used  for 
making  connection  with  the  service  pipe  in  the 
house. 

Located  at  the  left  of  C,  in  Fig.  58,  is  the 
curb-cock,  used  for  shutting  off  the  water  from 
the  city  lot.  The  curb-cock,  being  under- 
ground, is  reached  through  an  iron  tube  by 
means  of  a  wrench  attached  to  a  long  iron 
rod.  The  curb-cock  has  a  protective  covering 
in  the  form  of  an  iron  pipe.  The  lower  end  of 
the  pipe  screws  into  the  body  of  the  cock. 
The  top  end  comes  just  above  the  grade  line 
of  the  curb  and  is  covered  with  an  iron  screw- 
cap.  The  curb-cock  is  shown  in  detail  in  Fig. 
64.  The  pipe  B  is  fastened  to  the  valve  at  D  cockGas  jt  appears 
and  A  is  the  screw-cap.  In  opening  and  clos-  attached  to  the  ser- 
ing  the  wrench  fits  over  the  part  C  of  the  valve. 

On  entering  the  building  the  supply  pipe  should  be  provided 
with  a  stop  and  waste-cock  for  shutting  off  the  water  from  the 
house  and  draining  the  pipes  that  compose  the  system  of  circula- 
tion. At  V,  in  Fig.  58,  is  indicated  a  stop  and  waste-cock  with 


88  MECHANICS  OF  THE  HOUSEHOLD 

the  waste  pipe  B  connected  with  the  sewer.  This  cock  is  shown 
in  detail  in  Figs.  65  and  66.  The  cock  is  so  made  that  when 
closed  there  is  a  small  opening  at  A,  that  allows  the  water  from 
the  system  to  escape  through  the  waste  pipe. 

From  the  water  supply,  the  cold-water  pipes  may  be  traced  in 
the  drawing  directly  to  each  of  the  fixtures  of  the  house.  The 
hot-water  pipe  leaves  the  range  boiler  at  the  top  and  connects 
with  each  fixture  using  hot  water,  thus  making  the  circuit  com- 
plete. Details  of  the  piping  which  provides  hot  water  is  de- 
scribed under  range  boiler,  page  116. 


FIG  65. — Stop  and  drain     FIG.  66. — Stop  and  drain 
cock  with  lever  handle.  cock  with  T  handle. 


WATER  COCKS 

The  development  of  modern  plumbing  has  brought  about  the 
use  of  a  great  number  of  household  mechanical  appliances,  that 
have  received  trade  names  little  understood  by  the  average 
person.  The  lack  of  distinguishing  terms,  or  language  in  which 
to  describe  plumbing  fixtures,  often  leads  to  embarrassment, 
when  such  articles  are  to  be  described  to  workmen.  Common 
household  valves  and  cocks  are  so  classified  by  the  trade,  that 
mistakes  are  often  made  in  their  designation,  because  of  a  limited 
knowledge  of  the  use  of  the  various  articles.  A  little  considera- 
tion of  the  different  classes  of  fixtures  will  make  it  possible  to 
state  to  a  tradesman  the  exact  article  in  question. 

The  term  valve  is  intended  to  define  an  appliance  that  is  used 
to  permit,  or  prevent,  the  passage  of  a  liquid  through  the  open- 
ing or  port  which  it  guards.  The  term  is  so  general  in  its  appli- 
cation that  there  are  hundreds  of  different  kinds  of  valves. 
Even  for  a  single  purpose  there  are  many  styles  of  a  given  kind. 


PLUMBING 


89 


A  cock  was  originally  a  rotary  valve  or  spigot  used  for  draw- 
ing water.  Today  there  are  many  kinds  of  cocks  that  are  not 
rotary  in  their  movement. 

It  would  be  impossible  in  this  work  to  describe  in  detail  all 
of  the  kinds  of  cocks  and  valves  used  in  household  plumbing. 
It  will,  therefore,  be  the  aim 
to  confine  attention  to  one 
article  of  a  type  and  to  choose 
such  examples  as  are  in  general 
use  arid  that  are  good  repre- 
sentatives of  their  classes. 

Bibb-cocks. — On  the 
kitchen  sink,  the  water  fau- 
cets, such  as  those  shown  in 
Fig.  66a,  are  termed  bibb- 
cocks  by  the  plumber.  If  the 
nozzle  is  plain,  it  is  a  plain 
bibb.  If  the  nozzle  is  threaded 
so  that  a  hose  connection 
may  be  attached  as  in  Fig.  67,  it  is  a  hose  bibb.  Bibb-cocks  are 
found  in  three  general  styles:  compression  bibbs,  ground-key 
bibbs,  and  Fuller  bibbs.  The  compression  bibb  takes  its  name 
from  the  method  of  closing  the  valve.  Fig.  68  gives  an  ex- 
ample of  its  mechanical  construction.  This  is  a  plain  solder  bibb 


FIG.  660. — Kitchen  sink  with  Fuller 
bibb-cocks. 


FIG.  67. — Compres- 
sion hose  bibb. 


FIG.  68. — Compres- 
sion flange  bibb. 


FIG.  69. — Cross-section 
of  plain  compression  bibb- 
cock  for  a  solder  joint. 


because  the  shank  A  is  to  be  attached  by  a  solder  joint.  If  the 
part  A  contained  a  thread  to  make  a  screw  joint,  such  as  Fig. 
67,  it  would  be  a  plain,  compression,  screw  bibb.  Fig.  68  is 
another  style  of  compression  bibb-cock,  largely  used  on  sinks; 
this  cock,  being  finished  with  a  flange,  is  a  compression  flange  bibb. 


90 


MECHANICS  OF  THE  HOUSEHOLD 


Fig.  6§  shows  quite  clearly  the  mechanical  arrangement  of 
the  compression  cock.  When  the  handle  is  turned  the  nut  C  lifts 
the  valve  from  its  seat  B,  allowing  the  water  to  escape.  The 
piece  D  is  generally  made  of  composition  rubber  that  may  be 
bought  at  the  dealers  for  a  trifling  amount  but  it  may  be  re- 
placed temporarily  with  a  piece  of  leather.  The  part  E  is 
packing,  to  keep  the  water  from  leaking  out  around  the  stem. 
The  packing  may  be  obtained  from  the  dealer  especially  for  the 
purpose  or  it  may  be  made  of  a  disc  of  sheet  rubber.  In  fact, 
anything  that  can  be  put  into  the  space  will  answer  the  purpose 
temporarily.  The  valve  is  closed  by  compression,  hence  the 
name  compression  cock.  All  cocks  made  to  open  and  close  in  the 
same  manner  are  compression  cocks. 


FIG.  70. — Cross-sec-  FIG.  71. — Cross-sec-  FIG.  72. — Cross-section  of 
tion  of  plain  self-closing  tion  of  lever  handle,  plain  Fuller  bibb  for  lead 
bibb-cock  for  lead  pipe,  plain  bibb.  pipe. 

Self-closing  Bibbs. — In  Fig.  70  is  one  example  of  the  many 
styles  of  self-closing  bibb-cocks.  When  the  handle  of  this  cock 
is  turned,  the  steep- pitched  screw  A  opens  the  valve  and  at  the 
same  time  compresses  the  spiral  spring  B,  when  the  handle  is 
released,  the  valve  is  pressed  back  on  its  seat  by  the  spring. 
Self-closing  cocks  are  used  to  prevent  the  waste  of  water  at 
drinking  fountains,  wash  basins  and  other  places  where  the 
water  is  apt  to  be  left  running  through  carelessness. 

Lever-handle  Bibbs. — Fig.  71  is  an  example  of  the  lever- 
handle,  ground-key  bibb-cock.  The  key  is  the  piece  A,  which  is 
tapered  and  forms  a  ground  joint  with  the  part  -B.  The  cock 
takes  its  name  from  the  form  of  the  handle.  The  term  ground- 
key  means  that  the  key  has  been  ground  into  place  with  emery 
dust.  This  cock  is  kept  from  leaking  by  ad j  ustment  of  the  screw  C. 


PLUMBING  91 

Fuller  Cocks. — These  cocks  take  their  name  from  their 
inventer.  They  are  made  to  suit  every  condition  for  which 
water  cocks  are  used.  Their  universal  use  attests  to  their 
utility  and  excellence  in  service.  Fig.  72  shows  the  principle 
on  which  all  Fuller  cocks  work.  The  varying  conditions  under 
which  the  cocks  are  used  require  a  great  many  forms,  but  the 
working  principle  is  the  same  in  all.  In  these  cocks,  the  valve' 
is  a  rubber  plug  or  ball  that  is  drawn  into  the  opening  by  an 
eccentric  piece  attached  to  the  handle.  The  piece  D  in  the  draw- 
ing is  the  rubber  plug  that  is  drawn  against  the  opening  by  the 
crank  B,  which  is  worked  by  the  lever  handle  A.  This  cock  may 
be  repaired,  in  case  it  leaks,  by  unscrewing  it  at  the  joint  nearest 
the  plug.  A  wrench  and  a  pair  of  pliers  are  all  the  tools  required. 
The  pieces  D  must  be  obtained  from  the  dealer.  The  part  J  is 

Ball  Stem  with  Ball 


Eccentric  Handle 


FIG.  73. — Repairs  for  Fuller  cocks. 

the  packing  that  keeps  the  water  from  leaking  out  around  the 
stem.  The  screw- cap  H  forces  a  collar  /  down  on  the  packing 
to  keep  it  water-tight. 

The  parts  for  the  Fuller  cock  that  may  be  obtained  for  repair 
are  shown  in  detail  on  Fig.  73.  The  ball,  which  appears  in  Fig. 
73  at  D,  is  the  part  that  receives  the  greatest,  amount  of  wear. 
If  the  cock  at  any  time  fails  to  stop  the  flow  of  water,  a  new  ball 
may  be  put  in  place  by  the  aid  of  a  wrench  and  a  pair  of  pliers. 
The  water  being  first  shut  off  from  the  system,  the  cock  is  un- 
screwed and  the  cap  E  removed  with  a  pair  of  pliers.  The  worn 
ball  is  then  removed  and  a  new  one  substituted. 

Wash-tray  Bibbs. — A  special  style  of  cock  is  made  for  laundry 
wash  trays  in  both  the  Fuller  and  compression  types.  Of  these 
the  Fuller  type  is  the  most  convenient  as  the  handle  is  placed  on 
the  side  and  but  one  movement  is  required  to  open  the  cock. 
This  style  of  cock  is  used  on  the  wash  trays  shown  in  Fig.  83. 


92 


MECHANICS  OF  THE  HOUSEHOLD 


Basin  Cocks. — Water  cocks  for  wash  basins  are  made  in  two 
general  types — the  compression  and  the  Fuller  types  of  cocks. 

Their  mechanism  is  much  the  same  as 
for  other  similar  styles  adapted  to  the 
use  for  basins.  The  self-closing  cocks 
used  so  largely  on  wash  basins  are  com- 
pression cocks.  Fig.  74  is  an  example 
of  Fuller  basin  cock  in  general  use. 
Compression  cocks  for  the  same  purpose 
are  shown  on  the  wash  basin  in  Fig.  90. 
Pantry  Cocks. — In  general  form, 
pantry  cocks  are  the  same  as  those  used 
for  basins  except  that  the  outlet  is 
elongated. 

Sill  Cocks. — As  a  means  of  attaching 
garden  hose  or  lawn  sprinklers,  sill  cocks 
are  placed  on  the  side  of  the  building 
at  any  place  convenient  for  their  use. 
Fig.  75  illustrates  the  method  of  attach- 
ing the  cock  to  the  water  supply.     Fig.  76  shows  in  cross-section 
its  mechanical  arrangement.     The  part  A  is  screwed  into  the 
water  supply,  and  B  furnishes  the  hose  attachment.     The  valve 


FIG.   74.— Fuller  basin 
cock. 


FIG.  75. — Sill  cock  in  place  at- 
tached to  the  water  pipe. 


FIG.  76. — Cross  section 
of  sill  cock. 


is  operated  the  same  as  any  other  compression  valve.     In  Fig. 
75  the  cock  is  shown  at  A  with  a  garden  hose  attached.     The 


PLUMBING 


93 


pipe  to  which  A  is  attached  passes  into  the  basement  and  con- 
nects to  the  water  supply.  The  stop-cock  B  is  used  to  shut  off 
the  water.  When  the  stop-cock  B  is  closed,  A  should  be  opened, 
so  that  the  pipe  will  drain.  If  this  is  neglected  during  freezing 
weather,  the  pipe  is  apt  to  freeze  and  burst. 

Valves. — The  distinction  between  a  cock  and  a  valve  is  not  at 
all  definite.  Custom  has  determined  that  in  certain  places  a 
cock  shall  stop  the  flow  of  a  liquid  but  in  another  place,  perhaps 
of  a  similar  nature,  a  valve  shall  accomplish  the  same  purpose. 
The  chief  distinction  between  a  cock  and  a  valve  is  that  of  its 
external  form. 

In  Figs.  77,  78  and  79-  are  three  examples  of  valves  that  are 
very  generally  used  on  pipes  carrying  any  kind  of  fluid.  The 


C  H  } 


FIG.  77. — Cross-sec- 
tion of  globe  valve  with 
detachable  valve  disc. 


FIG.  78. — Cross-section 
of  angle  globe  valve. 


FIG.  79. — Cross-section 
of  gate  valve. 


valves   are  shown  in   cross-section  to  display  the  arrangement 
of  the  mechanism. 

Fig.  77  is  an  example  of  the  common  globe-valve.  The  name  was 
originally  intended  to  define  a  valve  the  body  of  which  was  in 
the  form  of  a  globe.  The  hand-wheel  H,  attached  to  the  screw- 
stem  S,  raises  the  valve  A  when  desired.  The  valve  makes  close 
contact  with  the  seat  C,  by  means  of  a  composition  rubber  disc 
B.  The  disc  B  may  be  renewed  when  worn  out  as  in  the  case  of 
the  radiator  valve  already  described. 


94  MECHANICS  OF  THE  HOUSEHOLD 


Fjg.  78  represents  an  angle  globe-valve.  In  general  construction 
it  is  quite  similar  to  Figs.  14  and  15,  but  the  valve  V  in  this  case 
is  a  cone-shaped  piece  of  brass,  which  makes  a  seat  in  a  depression 
provided  for  it.  The  valve  V  and  the  seat  are  formed  as  desired 
and  then  ground  into  contact  with  emery  dust  or  other  abrasive 
material,  to  assure  a  perfectly  tight  joint.  When  this  valve 
becomes  worn  and  begins  to  leak,  it  may  be  repaired  by  regrinding, 
but  such  work  requires  the  services  of  a  pipe-fitter.  The  tendency 
of  modern  practice  is  to  use  valves  with  the  detachable  discs,  such 
as  that  of  Fig.  77,  because  they  are  easily  repaired. 

The  valve  shown  in  Fig.  79  is  known  as  a  gate-valve.  The 
upper  part,  including  the  screw  and  stem,  is  the  same  as  the 
globe  style  but  the  valve  proper  is  made  in  the  form  of  two 
flat  gates  A-A.  When  the  valve  is  closed,  as  it  appears  in  the 
drawing,  the  gates  are  forced  against  the  seats  by  the  cone- 
shaped  piece  B,  which  acts  as  a  wedge,  to  tightly  close  the  opening. 
When  the  hand-wheel  is  turned  to  open  the  valve,  the  gates  are 
raised  and  are  taken  entirely  out  of  the  path  of  the  flowing 
liquid.  Gate-valves  are  used  in  places  where  it  is  desired  to 
obstruct  the  flow  as  little  as  possible.  They  are  somewhat  more 
expensive  than  globe-valves  but  are  considered  worth  the 
extra  expense  in  service. 

Kitchen  and  Laundry  Fixtures.  —  The  development  in  modern 
plumbing  has  wrought  many  changes  in  the  styles  of  household 
fixtures  but  none  has  been  so  great  as  that  in  the  kitchen  sink. 
The  old  style,  insanitary,  wooden  sink  has  been  almost  entirely 
replaced  by  those  made  of  pressed  steel  or  enameled  iron.  They 
are  made  in  every  desired  size  and  to  suit  all  purposes.  They 
may  be  plain  or  galvanized  as  occasion  may  require,  or  the  enam- 
eled sink  is  obtainable  at  a  very  slight  addition  in  price.  The 
enameled  sink  has  reached  a  degree  of  perfection  where  its  dura- 
bility is  unquestioned,  and  as  a  consequence  kitchen  furniture 
is  vastly  improved  at  but  little  advance  in  cost. 

A  modern  kitchen  in  which  gas  is  used  as  fuel  is  shown  in  Fig. 
80.  Simplicity  and  neatness  of  arrangement  are  the  noticeable 
features.  This  kitchen  is  intended  to  suit  the  average-sized 
dwelling  and  contains  all  necessary  plumbing,  cooking  and  heat- 
ing apparatus.  The  hot-water  boiler  is  here  shown  attached  to 
an  instantaneous  heater.  The  common  kitchen  sink  is  supple- 


PLUMBING 


95 


mented  with  a  slop  sink  and  covered  with  a  drain  board.     This 
simple  kitchen  may  be  elaborated  to  any  extent.     Fig.  81  shows 


FIG.  80.— Model  kitchen. 


FIG.  81. — White  enamel  kitchen  sink. 

a  kitchen  sink  of  white  enamel  with  two  enameled  drain  boards. 
The  drain  boards  are  sometimes  covered  with  perforated  rubber 
mats. 


96 


MECHANICS  OF  THE  HOUSEHOLD 


In  Fig.  82  is  shown  an  example  of  the  modern  basement  laun- 
dry.    The  wash-boiler  heater  is  shown  on  the  left.     An  auto- 


FIG.  82. — Model  laundry. 


FIG.  83. — Enamel  wash  trays  in  a  basement  laundry. 

matic  instantaneous  water  heater  is  on  the  right.     The  station- 
ary tubs  or  wash  trays  occupy  the  center  of  the  picture.     In  detail 


PLUMBING  97 

these  wash  trays  appear  in  Fig.  83.  These  are  enamel-covered 
ware  and  are  provided  with  the  wash-tray  bibb-cocks  described 
above.  This  type  of  plumbing  represents  the  most  modern  of 
sanitary  arrangements. 

THE  BATHROOM 

With  the  present-day  improvements  in  plumbing,  and  the 
perfection  in  the  manufacture  of  porcelain  and  enameled  iron, 
the  bathrooms  of  houses  of  moderate  cost  have  become  places  of 


FIG.  84. — Mode?  bath  room  for  the  average  dwelling. 

cleanliness,  attractive,  relatively  free  from  offending  odors  and 
supplied  with  all  necessary  sanitary  fixtures. 

Enameled  iron  has  reached  a  state  of  perfection  where  it  rivals 
porcelain  in  beauty.  The  forms  of  the  various  bathroom  pieces 
have  been  modeled  for  convenience  in  use  and  grace  of  form,  at 
the  same  time  the  strife  of  the  designer  has  been  to  produce 
articles  that  not  only  look  well  but  are  convenient  and  easily 
kept  clean. 

Bathrooms  need  not  be  expensive  in  order  to  be  convenient 
attractive  and  useful.  The  bathroom  shown  in  Fig.  84  is  such 
as  is  installed  in  dwellings  of  moderate  price.  It  possesses  every 
feature  necessary  to  usefulness  and  comfort.  In  this  room  the 

7 


98 


MECHANICS  OF  THE  HOUSEHOLD 


furnishings  are  all  of  enameled  iron.     The  floor  is  covered  with 
linoleum  and  the  wainscoting  with  enamel  paint. 

Bath  Tubs. — Bath  tubs  are  made  in  sizes  that  vary  in  length 
from  4J^  to  6  feet.  They  are  constructed  in  a  variety  of  forms 
and  of  materials  to  suit  all  conditions  of  service.  For  domestic 
use  they  are  very  generally  made  of  enameled  iron.  This  form 
of  construction  produces  serviceable  and  handsome  furnishings 
for  the  bathrooms  of  the  modest  house  as  well  as  for  the 
sumptuous  bath  of  the  most  pretentious  residence.  An  elabora- 
tion of  Fig.  84  might  include  the  Sitz  bath  shown  in  Fig.  85  and 

the  fittings  may  be  chosen 
from  a  great  variety  of  forms. 
The  recent  styles  of  enameled 
tubs  are,  in  design,  much 
handsomer  than  those  with 
the  roll  rim  and  in  form  such 
as  permits  a  clean  room  with 
the  minimum  of  labor.  They 
are  also  provided  with  more 
convenient  water  and  drain- 
age fixtures. 

The  tub  of  Fig.  86  sets  flat 
on  the  floor  and  makes  a  close 
joint  with  the  wall.  It  thus 
prevents  the  accumulation  of 

dust  that  is  difficult  to  remove.  In  addition  the  fixtures  are  ar- 
ranged in  a  more  commodious  manner  and  the  general  appearance 
is  most  pleasing.  The  arrangement  of  the  fixtures  in  Fig.  87  gives 
still  greater  convenience  and  being  arranged  with  a  shower  and 
protecting  curtain,  provides  all  of  the  conveniences  of  a  luxuri- 
ous bath  without  greatly  increased  cost  over  the  simple  tub. 
The  fixtures  in  this  design  are  all  in  position  of  greatest  con- 
venience and  attached  to  pipes  that  are  concealed  in  the  wall. 
The  fixtures  usually  provided  with  the  tub  are  double  Fuller 
or  compression  cocks  for  hot  and  cold  water,  the  overflow  and 
strainer,  for  the  discharge  of  the  water  into  the  sewer  in  case  the 
tub  overflows,  and  a  drain  and  bath  plug. 

The  double  Fuller  cock  is  shown  in  Fig.  88.     It  is  made  to  open 


FIG.  85.— Sitz  bath. 


PLUMBING 


99 


FIG.  86. — Enameled  iron  bath  tub. 


FIG.  87. — Bath  tub  with  shower. 


100 


MECHANICS  OF  THE  HOUSEHOLD 


and  close  by  the  same  sort  of  mechanism  as  is  shown  in  Fig.  71, 
a  description  of  which  appears  on  page  90. 

,The  overflow  is  shown  in  detail  in  Fig.  89.     The  part  A  appears 
inside  the  tub.     It  is  made  water-tight  around  the  edge  C  by  a 


FIG.  88. — Double  Fuller  cock  for  bath  tubs. 

rubber  washer  that  is  clamped  tight  to  the  surfaces  by  the  nut 
B.  In  case  of  leakage,  th^overflow  may  be  removed  for  repair 
by  unscrewing  the  union  attached  to  the  piece  D  and  removing 
the  nut  B. 


FIG.  89.  FIG.  89a. 

FIG.  89. — Overflow  attachment  for  bath  tubs,  lavatories,  etc. 
FIG.  89a. — Drain    attachment    for  bath  tubs,  avatories,  etc.,  showing  lock- 
nut  and  union  connection. 

The  drain-pipe  connection  is  shown  in  Fig.  89a.  The  plug  D 
and  the  flange  A  show  inside  the  tub.  The  flange  is  made 
water-tight  by  a  rubber  washer  that  the  nut  B  clamps  tight  to 
the  tub.  The  part  C  is  a  union  which  permits  the  tub  to  be 


PLUMBING 


101 


detached  from  the  drain  pipe.     Repairs  to  this  joint  may  be 
made  as  in  the  overflow. 


FIG.  90. — Old  style  marble  finished 
lavatory. 


FIG.  91. — Types  of  lavatory  plumbing 
not  now  used  in  good  practice. 


Wash  Stands  and  Lavatories. — Wash  stands  for  bathrooms  are 
obtainable  in  many  forms,  either  plain  or  ornate,  to  suit  every 
condition  and  style  of  architectural  finish. 


FIG.  92. — Enameled  iron  wall 
wash  basin. 


FIG.  93. — Enameled  iron  pedestal 
wash  basin. 


They  are  made  in  marble,  porcelain  and  enameled  iron,  the 
last  being  the  most  commonly  used.  They  are  made  to  suit  the 
part  of  the  room  to  be  occupied,  whether  that  is  against  a  wall, 


102 


THE  HOUSEHOLD 


a  corner,  or  to  stand  on  a  pedestal  on  the  floor.  Those  intended 
to  fasten  to  the  wall  may  be  supported  by  brackets  or  suspended 
at  the  back  from  pieces  secured  in  the  wall. 

In  Figs.  90  and  91  are  shown  samples  of  marble-finished  wash 
basins.  In  former  years  basins  of  this  type  were  very  much  in 
use,  and  until  the  introduction  of  the  modern  porcelain  and  en- 
ameled ware,  it  was  the  highest  type  of  sanitary  plumbing.  The 
water  cocks  and  traps  are  of  the  same  style  and  grade  as  appear 
on  the  most  modern  examples  of  enameled  ware  of  Figs.  92, 93  and 
94.  The  water  cocks  used  in  Fig.  90  are  of  the  compression  type. 

All  of  the  others  are  of  the  Fuller 
type.  The  basin  in  Fig.  93  is  pro- 
vided with  extra  shut-off  cocks  on 
the  water  pipe  under  the  basin.  They 
are  added  to  the  plumbing  merely  as 
a  convenient  means  of  shutting  off 
the  water  for  repair.  The  wash  stand 
is  usually  provided  with  hot  and  cold 
water  cocks,  a  waste  pipe  with  its 
traps  and  overflow  connections. 

Traps. — The  waste  pipes  from  the 
wash  basin  and  bath  tub  are  always 
provided  with  some  form  of  trap,  to 
prevent  air  from  entering  the  room 
from  the  sewer,  charged  with  offend- 
ing odors.  Traps  are  made  in  many 

forms,  but  the  purpose  of  all  is  to  prevent  the  escape  of  sewer  gas. 
The  plain  trap  S,  shown  in  Fig.  95,  is  that  used  under  the  ba's.in 
in  Fig.  91.  It  makes  a  tight  joint  by  means  of  the  nut  B  and  a 
rubber  washer  as  in  the  case  of  other  joints  of  the  kind.  The 
parts  C  and  E  are  unions  that  permit  the  pipe  or  bowl  to  be 
removed  without  disturbing  the  remainder  of  the  plumbing. 
From  the  form  of  the  trap  it  will  be  seen  that  the  U-shaped  part 
below  the  dotted  line  F  will  always  remain  full  of  water  and  so 
prevents  the  escape  of  air  from  the  sewer.  In  case  the  trap 
becomes  stopped  the  obstruction  will  likely  become  lodged  in 
this  part  of  the  pipe.  To  clean  the  trap  the  screw-plug  D  is 
taken  out  with  a  pair  of  pliers  and  the  obstruction  removed  with  a 
wire. 


FIG.   94. — Corner  wash  basin. 


PLUMBING 


103 


The  traps  used  in  Figs.  90  and  92  are  the  same  in  principle  as 

'  Fig.  95  but  are  made  to  discharge  into  a  pipe  placed  in  the  wall  in- 

. stead  of  under  the  floor.     The  trap  in  Fig.  94  is  a  form  known 

as  the  bottle-trap  that  is  sometimes  used  in  the  more  expensive 

plumbing. 

Another  style  much  used  with  lavatories  is  the  Bower  trap 
shown  in  Fig.  96.  In  this  trap  the  water  comes  down  the  pipe 
B  and  pushing  aside  the  hollow-rubber  ball  A,  enters  the  space 
surrounding  it  and  is  discharged  at  C.  The  ball,  being  light,  is 


FIG. 97 


B 


FIG.  98 


FIG.96 


FIG. 95 

FIG.  95. — The  S  trap  of  nickel-plated  brass  tubing. 
FJ^L  96. — The  Bower  non-siphoning  trap. 
I^r  97. — The  drum  type  of  norpsiphoning  trap. 
FIG.  98. — An  S  trap  made  of  lead  pipe. 

held  against  the  end  of  the  pipe  by  the  water  and  acts  as  a  stopper 
to  prevent  evaporation  from  taking  place.  Open  traps,  such  as 
Fig.  95,  if  left  standing  for  a  long  time,  may  lose  sufficient  water 
by  evaporation  to  destroy  the  water  seal  and  allow  the  sewer  gas 
to  escape.  In  the  use  of  the  Bower  trap  such  occurrence  is  much 
less  likely  to  take  place. 

Fig.  97  is  another  trap  much  used  on  sinks;  it  is  known  under 
the  trade  name  of  the  Clean  Sweep  trap.  The  part  C  is  much 
larger  than  the  common  trap  and  the  water  seal  is  less  likely  to 


104 


MECHANICS  OF  THE  HOUSEHOLD 


be  broken.  The  clean-out  is  larger  and  the  interior  is  easy  of 
access  in  case  of  stoppage. 

The  simplest  and  most  commonly  used  trap  in  cheap  plumbing 
is  that  of  Fig.  98.  It  is  a  lead  pipe  bent  in  the  form  of  an  S.  It 
is  the  same  in  shape  as  Fig.  95  and  performs  its  work  as  well  but 
does  not  have  the  means  of  detachment  shown  in  the  latter. 
Traps  of  many  other  forms  are  in  use  but  all  have  the  same 
function  to  perform  and  the  mechanical  make-up  is  much  the 
same  as  those  described. 

The  plan  of  attachment  of  the  various  bathroom  fixtures  of  the 
soil  pipe  must  always  depend  on  local  conditions.  The  object 


DETAIL   N 


DETAIL    L 

FIG.  99.  —  A  method  of  bath-room  plumbing  using  the  drum 


is  to  conduct  the  waste  water  to  the  sewer  in  such  a  way  as  to 
give  the  least  opportunity  for  stoppage  and  to  prevent  sewer  gas 
from  escaping  into  the  '  house.  To  accomplish  this  purpose  the 
pipes  and  traps  are  arranged  according  to  a  plan  proposed  by  the 
architect,  plumber  or  other  person  familiar  with  the  principles  of 
plumbing.  Since  these  pipes  are  placed  in  the  walls  and  under 
the  floors,  where  they  are  not  readily  accessible,  it  is  necessary 
that  their  arrangement  be  made  with  care  and  that  the  work- 
manship be  such  as  to  assure  correct  installation. 

In  Fig.  99  is  shown  a  common  method  of  connecting  bathroom 


PLUMBING  105 

fixtures  with  the  sewer.  The  drawing  shows  a  bathroom  with 
the  floor  broken  away  to  show  the  pipe  connections  with  the  bath 
tub,  wash  basin  and  closet.  The  overflow  pipes  0  and  V  and  the 
drain  pipes  D  and  R  from  the  .wash  basin  and  bath  tub  empty  into 
a  large  lead  drum-trap  T,  set  under  the  floor.  This  trap  takes  its 
name  from  its  shape.  It  is  set  in  position  as  dictated  by  the  condi- 
tions under  which  it  is  used.  The  nickeled  plate  P,  screwed  into 
the  top  of  the  trap,  comes  just  above  the  bathroom  floor.  This 
plate  is  easily  removed  in  case  of  stoppage.  It  is  made  air-tight 
by  a  rubber  ring  placed  under  the  cover  and  which  makes  a  joint 
with  the  top  edge  of  the  drum. 

It  will  be  noticed  that  the  waste  pipes  from  the  bath  tub  and 
wash  basin  enter  the  trap  near  the  bottom  and  discharge  at  the 
opposite  side  near  the  top.  The  water  will  stand  in  the  trap  and 
pipes  level  with  the  bottom  of  the  discharge  pipe  and  thus  form 
a  seal  that  prevents  the  escape  of  sewer  gas.  This  is  a  common 
form  of  non-siphoning  trap.  It  is  non-siphoning  because  it 
cannot  lose  its  seal  by  reason  of  the  siphoning  effect  of  the  water  _ 
as  it  passes  through  the  waste  pipes  on  its  way  to  the  sewer. 
Another  form  of  non-siphoning  trap  is  the  clean  sweep  trap  shown 
in  Fig.  97.  Such  traps  as  Figs.  95  and  98  are  siphoning  traps, 
since  it  is  possible,  in  this  form  of  trap,  for  the  water  to  be,  so 
completely  siphoned  that  not  enough  remains  to  form  a  seal. 
The  small  drawing,  marked  Detail  L,  is  another  method  of  con- 
necting the  same  arrangement  of  fixtures.  The  waste  pipe  enters 
the  trap  as  before  but  discharges  immediately  opposite.  The 
level  of  the  water  stands  in  the  pipes  as  indicated  by  the  dotted 
line^ 

Back-venting. — To  prevent  the  possibility  of  loss  of  seal  by 
siphoning  and  the  escape  of  sewer  gas,  traps  are  back-vented  to 
the  main  stack  or  to  a  separate  vent  stack.  The  venting  is 
accomplished  by  joining  a  pipe  to  the  top  of  the  trap  or  to  some 
point  in  its  immediate  neighborhood,  and  connecting  this  with 
the  main  stack  or  the  vent  stack.  The  water  in  a  trap  so  vented 
will  be  open  to  the  air  from  both  sides  and  consequently  can  never 
be  subject  to  siphonic  action. 

In  the  average-sized  dwelling  where  non-siphoning  traps 
are  used,  back-venting  is  not  necessary,  but  in  large  houses  and 


106 


MECHANICS  OF  THE  HOUSEHOLD 


in  plumbing  where  siphon  traps  are  used,  vent  pipes  must  be  at- 
tached to  the  traps  to  assure  a  satisfactory  system. 

Fig.  100  furnishes  an  example  of  back- venting,  applied  to  the 
bathroom  shown  in  Fig.  99.  In  the  former  figure  the  bath  tub 
and  wash  basin  are  connected  with  the  waste  pipe  by  siphon 
traps.  A  siphon  trap  may  lose  its  seal  in  two  ways:  by  self- 
siphonage,  or  by  aspiration  caused  by  the  discharge  of  the  water 
from  other  fixtures.  In  the  discharge  of  the  siphon  trap,  such 
as  B,  in  Fig.  100,  the  long  leg  of  the  siphon,  formed  by  the  dis- 
charge pipe,  may  carry  away  the  water  so  completely  that  not 
enough  remains  in  the  trap  to  form  a  seal.  Again,  the  discharge 
of  the  water  from  the  bath  tub  through  the  waste  pipe  tends  to 


FIG.   100. — An  exaSple  of  back-vented  plumbing  as  applied  to  the  bathroom. 


form  a  vacuum  above  it  and  in  some  cases  the  seal  in  B  is  de- 
stroyed by  the  water  being  drawn  into  the  vertical  pipe.  The 
possibility  of  either  of  these  occurrences  is  prevented  by 
back-venting. 

In  Fig.  100,  a  pipe  from  the  main  stack  is  connected  with  the 
bend  of  the  trap  at  B  and  also  to  the  waste  pipe  outside  the  trap 
at  T.  A  vent  is  also  taken  from  the  drain  C,  at  a  point  just 
below  the  trap  in  the  closet  seat.  The  object  of  all  of  the-vents 
is  to  prevent  the  tendency  of  the  formation  of  a  vacuum  from  any 


PLUMBING  107 

cause  that  will  carry  away  the  water  seal  of  the  trap  and  allow 
sewer  gas  to  enter  the  house. 

The  closet  seat  also  contains  a  trap  which  will  be  described 
later.  It  connects  with  soil  .pipe  S,  leading  to  the  sewer  by  a 
large  lead  pipe  C. 

All  of  the  pipes  under  the  floor,  leading  to  the  soil  pipe,  should 
be  of  lead.  The  pipes  above  the  floor  are  generally  of  iron  or 
nickel-plated  brass.  All  of  the  connections  in  the  lead  pipes  are 
made  with  wiped  joints;  that  is,  the  connections  are  made  by 
wiping  hot  solder  about  the  joint,  in  a  manner  peculiar  to  this 
kind  of  work,  in  such  a  way  as  to  solder  the  pipes  together.  The 
joints  made  in  this  manner  are  perfectly  and  permanently  tight. 
Lead  pipes  are  used  under  such  conditions,  because  lead  is  the 
least  affected  by  corrosion  of  any  of  the  metals  that  could  be 
used  for  such  work. 

Soil  Pipe. — The  soil  pipe,  of  whichjj 
drain  is  composedTis  made  of  cast  iron  and  comes  from  the  factory 
covered  with  asphaltum  paint.  It  may  be  obtained  in  two 
grades,  the  standard  and  extra  heavy.  The  only  difference  is  in 
the  thickness  of  the  pipe.  The  former  is  commonly  used  in  the 
average  dwelling.  One  end  passes  through  the  roof  and  the  other 
end  joins  to  the  vitrified  sewer  tile  under  the  basement  floor. 
The  joints  must  be  perfectly  tight,  because  a  leak  in  this  pipe 
would  allow  sewer  gas  to  escape  into  the  house.  One  end  of 
each  section  is  enlarged  sufficiently  to  receive  the  small  end  of 
the  next  section.  The  joints  are  made  with  soft  lead.  The 
pipes  are  set  in  place  and  a  roll  of  oakum  is  packed  into  the  bot- 
tom of  the  joint,  after  which  molten  lead  is  poured  into  the 
joint,  filling  it  completely.  The  oakum  is  used  only  to  keep  the 
lead  in  the  joint  until  it  cools.  After  the  lead  has  cooled  it  is 
packed  solidly  into  the  joint  with  a  hammer  and  calking  tool. 
The  calking  is  necessary  because  the  lead  shrinks  on  cooling 
and  makes  a  joint  that  is  not  tight.  Well-calked  joints  of  this 
kind  are  air-tight  and  permanent.  Detail  N  (Fig.  99)  shows  the 
arrangement  of  the  parts  of  the  joint  as  indicated  at  A.  The 
blackened  portion  represents  the  lead  as  it  appears  in  the  joint. 

Detail  M  (Fig  99)  shows  the  methods  of  attaching  the  closet 
seat  to  the  lead  waste  pipe  C.  The  end  of  the  lead  pipe  is  flanged 
at  the  level  of  the  floor,  as  shown  at  C  in  the  detail  drawing. 


108 


MECHANICS  OF  THE  HOUSEHOLD 


The  depression  D,  around  the  connection,  is  then  filled  with 
glazier's  putty  and  the  seat  is  forced  down  tightly  in  place  and 
fastened  with  lag  screws. 

The  pipe  C,  from  the  closet,  and  that  from  the  trap  T,  being  of 
lead,  a  special  joint  is  necessary  in  connecting  them  with  the  soil 
pipe,  because  a  wiped  joint  cannot  be  made  with  cast  iron.  To 
make  such  a  connection  the  end  of  the  lead  pipe  is  " wiped"  onto 
a  brass  thimble,  heavy  enough  to  allow  it  to  be  joined  to  the  soil 
pipe  by  a  calked  lead  joint.  The  brass  thimble  is  then  joined  to 
the  cast-iron  pipe  by  a  calked  lead  joint. 

Water  Closets. — Water  closets  are  made  in  a  great  number  of 
styles  to  suit  the  architectural  surroundings  and  the  various 
conditions  under  which  they  are  to  be  used.  Many  forms  of 


FIG.   101.— The  wash-out 
closet. 


FIG.   102. — The  wash-down 
closet. 


water  closets  are  manufactured  to  conform  to  special  conditions, 
but  those  commonly  used  in  the  bathrooms  of  dwellings  are  of 
three  general  types.  The  mechanical  construction  of  each  is 
shown  in  the  following  drawings,  Figs.  101,  102  and  103  showing 
respectively  in  cross-section  the  principle  tjf  operation  of  the 
washout  closet,  the  washdown  closet  and  "the  siphon-jet  closet. 
Washout  Closets. — This  type  ofcloset  has  in  the  past  been 
used  to  a  very  great  extent.  It  does  not  perform  the  work  it  has 
to  do,  so  perfectly  as  the  others,  because  the  shallowness  of  the 
water  in  the  bowl  allows  it  to  give  off  odors,  and  because  it  is 
difficult  to  keep  clean.  The  action  of  the  closet  is  as  follows: 
When  the  closet  is  flushed  the  water  enters  the  rim  at  A ,  and  the 
greater  portion  of  it  is  washed  downward  at  B  to  dislodge  the 
contents  of  the  bowl.  A  lighter  flush  is  sent  through  the  openings 


PLUMBING  109 

in  the  side,  which  serves  to  wash  the  entire  surface.  The  direc- 
tion of  discharge  is  forward,  where  it  dashes  against  the  front 
of  the  bowl  and  then  falls  into  the  trap.  The  only  force  received 
to  carry  the  water  to  the  trap  is  from  falling  through  the  distance 
from  the  point  where  it  strikes  the  front.  The  flushing  action 
is  obtained  from  the  use  of  a  large  volume  of  water.  As  the 
discharged  matter  is  dashed  against  the  front  of  the  bowl,  the 
flushing  action  of  the  water  is  not  sufficient  to  remove  all  the 
stains;  the  result  is  an  accumulation  of  filth.  This  part  of  the 
bowl  is  out  of  sight;  hence,  it  is  seldom  kept  clean.  The  name 
washout  comes  from  the  action  of  the  water  to  wash  out  the  con- 
tents of  the  bowl. 


FIG.   103. — The  siphon-jet       FIG.   104. — A  poor  design  of 
closet.  wash-down  closet. 

Washdown  Closets. — As  shown  in  Fig.  102,  the  action  of  this 
closet  is  to  wash  the  contents  of  the  bowl  directly  down  the  soil 
pipe.  The  depth  of  the  water  at  A  is  much  greater  than  at  the 
corresponding  point  in  the  washout  closets;  as  a  consequence 
fecal  matter  is  almost  submerged.  The  main  objection  to  this 
closet  is  that  it  is  noisy.  Fig.  104  shows  another  form  of  wash- 
down  closets.  This  closet  is  open  to  objection  because  of  faulty 
design;  the  part  A  is  difficult  to  keep  clean  because  of  its  shape. 

Siphon -jet  Closet. — What  is  considered  by  many  to  be  the 
most  satisfactory  closet  yet  designed,  is  that  of  the  siphon-jet 
type  shown  in  Fig.  103.  The  flushing  action  of  this  closet  is 
entirely  different  from  that  of  the  others  described.  The  flush- 
ing water  enters  at  A  and  fills  the  rim  B.  Part  of  the  water 
washes  the  sides  of  the  bowl,  while  the  remainder  flows  through 
the  jet  C,  and  is  discharged  directly  into  the  outlet.  The  ejected 
water  enters  the  outlet  D,  which,  as  soon  as  it  fills,  acts  as  a 
siphon  to  draw  the  water  into  the  soil  pipe.  This  closet  is  most 


110 


MECHANICS  OF  THE  HOUSEHOLD 


positive  in  its  action,  since  the  discharge  is  made  by  the  siphon 
and  also  receives  the  additional  momentum  due  to  the  water 
flowing  through  the  jet.  Its  action  is  attended  with  but  little 
noise. 

Flush  Tanks. — The  water  closet  depends  for  its  action  on  one 
of  two  general  types  of  flush  tanks,  the  high  and  the  low  forms. 
The  tank  is  automatically  filled  with  water  and  when  wanted,  a 


FIG.     105. — Siphon-jet    closet 
with  the  high  flush  tank. 


FIG.   106. — Form  of  closet  not 
now  used  in  good  practice. 


large  volume  of  water  is  suddenly  discharged  into  the  sewer, 
carrying  with  it  the  contents  of  the  seat.  The  tank  again  fills 
and  is  ready  for  use  when  required. 

As  illustrations  of  high  flush  tanks,  those  shown  in  Figs.  105 
and  106  furnish  examples  of  a  simple  and  efficient  form.  The 
details  of  the  mechanism  of  this  type  of  tank  are  shown  in  Fig. 
107.  The  pipe  from  the  water  supply  is  attached  at  G  to  the 
automatic  valve  F,  which  keeps  the  tank  filled  with  water.  The 
piece  F  of  the  valve  is  held  against  the  opening  by  the  pressure 
exerted  through  the  float  E.  The  float  is  a  hollow  copper  ball. 


PLUMBING 


111 


As  the  ball  is  lifted  it  exerts  a  pressure  in  proportion  to  the 
amount  it  is  submerged.  When  the  water  reaches  the  level 
A-A,  the  valve  is  tightly  closed.  As  the  water  is  discharged 
from  the  tank  the  ball  follows  the  level  of  the  water  and  opens 
the  valve,  allowing  the  water  to  enter  and  again  fill  the  tank. 
The  siphon  is  made  of  cast  iron,  and  in  the  figure  is  shown  cut 
through  the  center.  The  lower  end  fits  loosely  in  the  piece  K, 
and  makes  a  water-tight  joint  around  its  outer  edge,  by  resting 
on  a  rubber  ring  C-C.  The  right-hand  side  of  the  siphon  is 
open  at  H,  and  when  the  tank  is  full,  the  level  of  the  water  is  at 
A-A,  which  is  almost  at  the  top  of  the  division  plate.  To  dis- 
charge the  tanjs.,  the  chain  L,  attached  to  the  lever  B,  is  pulled 
down;  this  action  raises  the  siphon  from  its  seat.  As  soon  as  the 
siphon  is  lifted,  the  water  rushes  through  the  opening  around 


FIG.   107. — Details  of  construction  of  a  simple  type  of  siphon  flush  tank. 

C-C,  into  the  pipe  K;  this  causes  a  partial  vacuum  to  form  in  Z>, 
arid  the  water  is  lifted  over  the  division  platfe  K,  and  flows  out 
at  D,  forming  the  siphon.  As  soon  as  the  siphonic  action  begins 
the  siphon  may  be  dropped  back  on  the  seat  and  the  water  will 
continue  to  discharge  until  the  tank  is  empty. 

Low-down  Flush  Tank. — The  low-down  flush  tank  for  water 
closets  has  met  with  so  much  favor  that  it  has  to  a  great  extent 
displaced  the  high  tank.  The  reason  for  this  is  because  of  its 
advantages  over  the  other  style.  The  low  tank  is  more  accessible, 
more  easily  kept  clean,  and  better  adapted  to  low  ceilings. 
It  is  used  successfully  as  a  siphon  tank,  but  other  forms  are  in 
use  with  satisfactory  results. 

Fig.  108  gives  a  perspective  view  of  one  style  of  this  type  of 
tank  attached  to  a  siphon-jet  closet.  Figs.  109  and  110  give  the 


112 


MECHANICS  OF  THE  HOUSEHOLD 


details  of  the  construction  of  two  forms  of  this  type  of  tank,! 
both  of  which  have  given  efficient  service.     The  drawing  shows 
the  tanks  with  the  front  broken  away  to  give  a  view  of  the  work- 
ing parts.     The  water  enters  the  tank  and  is  discharged  at  the ; 
points  indicated.     The  float  and  supply  valve  works  exactly  as 
described  in  the  high  tank.     The  drawing  in  Fig.   109  shows 
the  tank  in  the  act  of  discharging.     The  .discharge  valve  is  raised 
as  shown  at  E.     When  the  water  is  completely  discharged,  the 
float  occupies  the  position  shown  dotted.     When  the  float  reaches 
this  dotted  position,  its  weight  pulls  down  the  piece  A.     This 


FIG.  108. — Siphon- 
jet  closet  with  low- 
down  tank. 


FIG.   109.  —  Details    of    construction 
flush  tank. 


low-down 


releases  the  lever  B,  and  the  attached  stopper  E,  which  falls  and 
closes  the  discharge  orifice.  While  the  tank  is  filling  with  water, 
a  stream  flows  through  the  small  pipe  D,  to  replenish  the  water 
in  the  closet  that  has  been  discharged  in  siphoning.  When  the 
tank  is  full  of  water,  the  pieces  A  and  B  occupy  the  positions 
shown  dotted.  ,«  To  discharge  the  tank  the  trip  is  pushed  down. 
This  action  raises  the  lever  to  the  position  B,  and  with  it  the 
attached  stopper  E.  The  piece  C  falls  and  the  opposite  end  A 
holds  B  suspended  until  the  tank  is  completely  discharged. 
The  action  of  the  tank  shown  in  Fig.  110  is  the  same  as  the 
others  except  that  of  the  discharge  mechanism.  In  the  drawing, 
the  tank  is  full  of  water  ready  to  be  discharged  when  required, 


PLUMBING 


113 


A  hollow  rubber  ball  E  serves  as  a  stopper  for  the  discharge 
pipe.  The  ball  is  kept  in  place,  when  the  tank  is  filling,  by  the 
pressure  of  the  water  above  it.  The  discharge  is  started  by  press- 
ing down  the  trip  on  the  front  of  the  tank.  This  raises  the  ball 
from  its  seat,  and  being  lighter  than  water,  it  floats,  thus  leaving 
the  discharge  pipe  open  until  the  tank  is  empty,  when  the  ball 
is  again  back  on  its  seat.  As  the  tank  fills  the  pressure  of  the 
water  above  prevents  the  ball  from  again  floating,  until  lifted 
from  its  seat.  The  supply  valve  and  refilling  pipe  D  is  the  same 
in  action  as  in  the  other  tank. 


FIG.   110. — Details  of  construction  of  the 
float-valve,   low-down  flush  tank. 


FIG.  111.— Method  of 
using  the  plumber's  friend, 
in  removing  obstructions. 


Opening  Stopped  Pipes.- — It  occasionally  happens  that  pipes 
leading  from  the  various  toilet  fixtures  become  stopped  because  of 
accumulations  or  by  articles  that  accidentally  pass  the  entrance. 
In  case  the  pipe  has  a  trap  connection  the  stoppage  is  most  likely 
to  occur  at  that  point.  Usually  the  obstruction  may  be  removed 
by  detaching  the  screw-plug  of  the  trap  and  removing  the  accu- 
mulation with  a  wire. 

Closet  seats  furnish  an  inviting  receptacle  for  waste  material 
of  almost  every  kind.  Stoppages  are  not  uncommon  and  are 
generally  found  in  the  trap.  One  method  of  removing  obstruc- 
tion is  by  use  of  the  plumbers'  friend.  This  device  is  shown  at 

8 


114 


MECHANICS  OF  THE  HOUSEHOLD 


P-R,  in  Fig.  111.     It  consists  of  a  wooden  handle  P  attached  to 
a  cup-shaped  rubber  piece  R. 

The  plumbers'  friend  is  shown  in  the  figure,  placed  to  remove 
an  obstruction  S  that  is  lodged  in  the  trap.  A  sudden  downward 
thrust  causes  the  rubber  cap  R  to  entirely  fill  the  closet  outlet 
and  the  resulting  pressure  to  the  water  is  generally  sufficient 
to  force  the  obstruction  through  the  trap  to  the  soil  pipe. 

The  kitchen  sink  is  another  place  that  affords  opportunity 
for  accumulation  that  stops  the  waste  pipe.  Accumulation  of 

grease  in  the  trap  is  a  "common 
cause  of  trouble.  This  may  be 
remedied  to  some  extent  by  the 
use  of  potash  or  caustic  soda. 
When  the  pipe  is  stopped  and 
the  trouble  cannot  be  reached 
from  the  trap,  a  common  method 
of  removing  the  stoppage  is  that 
suggested  in  Fig.  112.  A  piece 
of  heavy  rubber  tubing  is  forced 
over  the  water  tap  and  the  other 
end  tightly  wedged  into  the  drain 
pipe;  the  water  is  then  turned 
on  and  generally  the  pressure  is  sufficient  to  force  the  accumu- 
lation down  the  pipe. 

Sewer  Gas. — The  prevalent  fear  of  the  deleterious  effect  of 
escaping  sewer  gas  is  one  that  has  been  magnified  to  an  un- 
warrantable degree.  Among  bacteriologists  it  is  very  generally 
recognized  that  none  of  the  dreaded  diseases  to  which  the  human 
kind  is  susceptible  are  transmitted  by  gases.  The  one  possible 
harmful  effect  recognized  in  sewer  gas  by  scientists  is  that  pro- 
duced by  carbon  monoxide.  Sewer  gas  often  contains,  from  es- 
caping illuminating  gas,  sufficient  carbon  monoxide  to  produce 
the  poisoning  effect  characteristic  of  that  gas  but  the  possibility 
of  danger  is  quite  remote.  The  leakage  of  sewer  gas  is  detected 
by  the  sense  of  smell  sooner  than  in  almost  any  other  way. 
While  leaks  in  sewer  pipes  are  unhygienic  in  that  they  are  con- 
ducive to  undesirable  atmospheric  conditions,  they  should  not  be 
looked  upon  as  the  agents  through  which  transmissible  diseases 
are  carried. 


FIG.  112. — Method  of  removing  ob- 
structions from  a  stopped  drain-pipe. 


PLUMBING  115 

To  the  average  person  the  term  sewer  gas  conveys  the  impres- 
sion of  a  particularly  loathsome  form  of  vaporous  contagion, 
capable  of  distributing  every  form  of  communicable  disease.  To 
the  scientific  mind  it  means  np  more  than  a  bad  odor.  Sewer  gas 
is  really  nothing  but  ill-smelling  air. 

RANGE  BOILERS 

The  hot-water  supply  to  the  household  is  of  so  much  impor- 
tance, that  the  installation  of  the  range  boiler  should  be  made 
with  great  care,  and  an  understanding  of  the  principle  on  which 
it  works  should  be  fully  appreciated  by  all  who  have  to  do 
with  its  management.  The  ability  of  the  boiler  to  supply  the 
demands  put  upon  it  depends  in  a  great  measure  on  its  size  and 
the  arrangement  of  its  parts,  but  proper  management  is  necessary 
to  assure  a  supply  of  hot  water  when  required. 

Range  boilers  are  used  for  storing  hot  water  heated  by  the 
water-back  of  the  kitchen  range  or  other  water  heater,  during  a 
period  when  water  is  not  drawn.  It  serves  as  a  reserve  supply 
where  the  heater  is  not  of  sufficient  size  to  heat  water  as  fast  as 
is  demanded. 

As  commonly  used,  range  boilers  are  galvanized-steel  tanks 
made  expressly  for  household  use.  They  are  standard  in  form 
and  may  be  bought  of  any  dealer  in  plumbing  or  household 
supplies.  In  capacity  they  range  from  20  to  200  gallons  and  are 
made  for  either  high-  or  low-pressure  service.  They  are  said  to 
be  tested  at  the  factory  to  a  pressure  of  200  pounds  to  the  square 
inch  and  are  rated  to  stand  a  working  pressure  of  150  pounds. 
Range  boilers  are  galvanized  after  they  are  made  and  coated 
both  inside  and  out.  The  coating  of  zinc  received  in  the  galva- 
nizing process  helps  to  make  their  seams  tight  and  at  the  same 
time  renders  the  surface  free  from  rust. 

There  is  no  definite  means  of  determining  the  size  of  tank 
to  be  used  in  any  given  case,  because  of  the  varying  demands 
of  a  household  but  a  common  practice  is  to  allow  5  gallons  in 
capacity  to  each  person  the  house  is  able  to  accommodate. 

The  Water-back. — The  most  common  method  of  heating  water 
for  the  range  boiler  is  by  use  of  the  water-back  or  water-front  of 
the  kitchen  range.  The  water-back  is  a  hollow  cast-iron  piece 


116 


MECHANICS.  OF  THE  HOUSEHOLD 


that  is  made  to  take  the  place  of  the  back  fire-box  lining  of  the 
range.  In  some  ranges  the  heater  occupies  the  front  of  the 
fire-box  instead  of  the  back,  in  which  case  the  heater  becomes 
the  water-front. 

The  arrangement  of  pipes  connecting  the  source  of  water 
supply  with  the  boiler  is  such  that  cold  water  is  constantly 
supplied  to  the  tank  as  the  hot  water  is  drawn.  If  no  water  is 

drawn  from  the  tank,  it  will  continue 
to  circulate  through  the  tank  and 
heater,  the  water  becoming  constantly 
hotter. 

The  connecting  pipes  are  usually  of 
iron  but  sometimes  pipes  of  copper 
or  brass  are  used.  The  joints  should 
be  reamed  to  remove  the  burr  that 
is  formed  in  cutting.  The  angles 
should  be  45-degree  bends  or  better 
still  90-degree  bends  in  connecting  the 
heater  with  the  tank  so  as  to  cut  down 
the  amount  of  friction  as  much  as 
possible. 

In  Fig.   113  is  shown  a  standard 
range  boiler  connected  to  the  range. 
The  water  is  brought  into  the  top  of 
FIG.   113.  — A  common    the  tank  through  the  pipe  a-a,  and 

bol^lolheTater'-back"311^     PaSsin«    thrOUSh   i(;   enters  the  water- 

back  by  means  of  the  pipe  b.     After 

passing  through  the  water-back  the  water  again  enters  the  tank 
through  the  pipes  c  and  d,  as  indicated  by  the  arrow.  The 
flow  pipe  (carrying  the  out-going  water)  from  the  water-back 
may  be  connected  with  the  tank  at  e,  as  shown  dotted  or  in 
some  cases  the  connections  are  made  at  both  places.  The  veloc- 
ity of  circulation  depends  on  the  vertical  height  of  the  column 
of  hot  water  and  the  greater  height  will,  therefore,  improve  the 
circulation  and  thus  increase  the  efficiency  of  the  heater.  The 
circulation  of  the  water  through  the  tank  and  heater  is  pro- 
duced by  its  change  in  weight  as  the  water  is  heated.  As  the 
hot  water  comes  from  the  water-back  it  rises  in  the  pipe  because 
it  is  lighter  in  weight  than  the  cooler  water  of  the  tank.  In 


PLUMBING  117 

the  case  of  the  pipe  shown  dotted  in  Fig.  113  the  longer  ver- 
tical rise  will  give  a  greater  upward  velocity  of  the  hot  water 
and  consequently  a  better  circulation  through  the  entire  circuit. 

The  construction  of  the  water-back  is  shown  in  the  small 
drawing.  The  connections  are  made  at  b  and  c  as  before.  A 
division  plate  in  the  water-back  causes  the  water  flowing  in  at 
b  to  follow  the  length  of  the  heater  at  the  bottom  and  return  at 
the  top  as  indicated  by  the  arrow,  when  it  is  discharged  at  C. 

The  hottest  water  is  always  at  the  top  of  the  tank  and  the 
temperature  grades  uniformly  from  the  hottest  at  the  top  to 
the  coolest  at  the  bottom.  The  reason  for  extending  the  pipe 
a  so  far  down  into  the  tank  is  that  the  cold  water  may  not 
mingle  with  the  hot  water  and  reduce  its  temperature  on  entering 
the  tank.  Near  the  top  of  the  pipe  a  is  a  small  hole  /  that  is  in- 
tended to  prevent  the  water  from  being  siphoned  from  the  tank 
in  case  a  vacuum  is  formed  in  the  cold-water  pipe.  In  this  ar- 
rangement the  water  enters  and  leaves  at  the  top  of  the  tank. 
In  case  the  supply  is  shut  off  at  any  time  the  tank  is  left  almost 
full  of  water,  because  the  siphoning  effect  cannot  extend  below 
the  small  hole  /. 

Excessive  Pressure. — Accidents  due  to  the  explosion  of  hot- 
water  backs  are  not  at  all  rare  and  it  should  be  borne  in  mind 
that  there  is  danger  of  excessive  pressure  being  formed  should 
the  pipes  b  and  c  become  stopped.  Under  normal  conditions 
the  pressure  generated  by  the  heated  water  is  relieved  by  the 
water  in  the  tank  being  forced  back  into  the  supply  pipe.  The 
pressure  in  the  tank,  therefore,  cannot  become  greater  than  that 
of  the  source  of  supply,  but  if  b  and  c  should  become  stopped 
with  the  water-back  full  of  water  a  dangerous  pressure  might 
result.  The  greatest  danger  from  this  cause  is  that  of  freezing. 
It  frequently  happens  that  houses  are  closed  during  cold  weather 
and  the  water-back  is  left  undrained.  The  water  freezes  and 
when  a  fire  is  started  in  the  range,  the  ice  in  the  water-back 
is  the  first  to  melt.  In  a  short  time  steam  will  be  generated  that 
will  soon  produce  a  sufficient  pressure  to  burst  the  water-back. 
This  has  happened  many  times  with  disastrous  results.  Such 
dangers  may  be  avoided  by  the  exercise  of  a  reasonable  amount 
of  care  in  the  management  of  the  range.  To  drain  the  water- 
back,  the  water  is  first  shut  off  at  the  point  where  the  supply 


118 


MECHANICS  OF  THE  HOUSEHOLD 


Hot 
Water 


FIG.  114.— Blow-off 
for  removing  sedi- 
ment. 


pipe  enters  the  house.     The  water  in  the  range  boiler  is  then 
drawn  off  by  means  of  the  cock  h. 

Blow-off  Cock. — When  a  considerable  amount  of  sediment 
is  carried  in  the  water  the  range  boiler  acts 
as  a  settling  tank  and  the  deposit  accumu- 
lated at  the  bottom  will  in  time  amount  to 
a  source  of  trouble.  The 
accumulation  is  shown  in 
Fig.  114.  The  part  W, 
which  connects  with  B, 
is  sometimes  provided 
with  a  blow-off  cock 
that  will  admit  of  a  dis- 
charge of  the  sediment. 
More  commonly  the 
piping  is  arranged  as 
shown  in  Fig.  113,  when 
sediment  is  removed  by 
occasionally  drawing 
water  from  the  cock  h. 

Location  of  Range  Boiler. — It  is  some- 
times desired  to  place  the  range  boiler  on  a 
different  floor,  either  above  or  below  the 
range.  While  such  arrangements  are  entirely 
possible  the  circulation  of  the  water  is  not  so 
good  as  that  described  above.  The  weight 
of  the  two  columns  of  water  in  the  connecting 
pipes  are  so  nearly  balanced  that  good  cir- 
culation is  not  always  possible.  In  Fig.  115 
the  connections  are  shown,  where  the  tank 
is  located  in  the  basement.  In  connecting 
the  water-back  to  the  tank  under  such  con- 
ditions the  piping  is  relatively  the  same 
as  is  shown  in  the  dotted  connections  of  Fig. 
113,  but  the  connections  are  longer.  The 
circulating  pipe  comes  from  the  bottom  of 
the  tank  and  leads  to  the  bottom  of  the  water-back.  The  flow 
pipe  from  the  top  of  the  water-back  is  extended  up  to  a  distance 
equal  or  greater  than  the  distance  from  the  water-back  to  the 


Cold 
Water 


FIG.  115.— Method 
of  connecting  the  range 
boiler  when  placed  on 
the  floor  below  the 
heater. 


PLUMBING 


119 


bottom  of  the  tank.     The  hot  water  is  taken  from  the  top  of 
the  flow  pipe  at  any  place  above  the  tank. 

Double  Heater  Connections. — Two  heaters  are  sometimes  con- 
nected to  one  range  boiler,  each  circuit  being  independent  of 
the  other.  Under  such  conditions  one  or  both  heaters  may  be 
used.  When  the  tank  is  connected  as  shown  in  Fig.  116  the  pipe 
a,  from  the  bottom  of  the  tank,  branches  and  leads  to  b  and  &', 
at  the  bottom  of  each  of  the  heaters.  The  flow  pipes  from  the 
top  of  the  heaters  enter  the  tank  at  separate  places,  the  lower 
heater  sending  its  water  into  the  side  of  the 
tank  at  c,  and  the  upper  heater  flowing  into 
the  pipe  d,  at  the  top  of  the  tank.  It  would 
be  perfectly  possible  to  reverse  the  connec- 
tions for  the  flow  pipes  in  the  arrangement 
of  Fig.  116  and  attain  the  same  results. 
In  such  combinations  the  heaters  are  some- 
times piped  tandem,  the  water  flowing 
through  each  of  the  heaters  in  turn.  This, 
however,  is  not  the  best  method  to  employ, 
for  if  only  one  of  the  heaters  is  used  the 
second  acts  to  cool  the  water. 

Horizontal  Range  Boilers. — It  occasion- 
ally happens  that  in  a  small  kitchen  there 
is  no  convenient  floor  space  for  the  range 
boiler  and  it  becomes  necessary  to  suspend 
it  from  the  ceiling.  It  is  perfectly  possible 
to  station  the  ordinary  range  boiler  in  such 
a  position  and  have  it  work  fairly  well  but 
from  the  location  of  the  cold-water  inlet, 
only  that  part  of  the  range  boiler  above  the 
cold  water  pipe  is  actually  used  for  storage. 
The  water  in  the  lower  half  constantly  mixes 
with  the  entering  cold  water  before  it  is 
heated  by  passing  through  the  water-back.  When  hot  water 
is  drawn  from  the  top  of  the  range  boiler,  cold  water  enters  by 
the  cold-water  pipe  and  reduces  the  temperature  of  most  of  the 
lower  half.  Fig.  117  illustrates  such  an  arrangement.  In  this 
case  the  pipes  connected  with  the  water-back  are  those  that  cor- 
respond to  the  circulating  pipes  a  and  e  in  Fig.  113. 


FIG.  116.— Double 
connections  for  the 
range  boiler  where  a 
heater  is  placed  in 
the  basement  for  oc- 
casional use. 


120 


MECHANICS  OF  THE  HOUSEHOLD 


Suppose  the  range  boiler  is  full  of  water,  and  that  it  is  being 
heated.  The  lower  pipe  at  the  left-hand  end  is  conducting  the 
water  to  the  water-back  and  it  is  being  returned  to  the  range  boiler 
by  the  upper  pipe  at  the  same  end.  When  the  hot  water  is 
drawn  from  the  top  of  the  range  boiler  by  the  hot-water  pipe, 
the  entering  cold  water  mixes  with  hot  water  in  most  of  the 

i  lower  half  of  the  range  boiler 
before  it  has  been  heated  by 
passing  through  the  water- 
back  and  so  reduces  the  tem- 
perature of  most  of  the  lower 
half  of  the  tank. 

A  much  better  tank  for  the 


Hot  Water 


Water 
Back 


Water 


FIG.  117. — Method  of  con- 
necting the  vertical  range-boiler 
in  a  horizontal  position. 


FIG.   118. — Horizontal  range-boiler  sus- 
pended from  the  ceiling. 


purpose  is  that  indicated  in  Fig.  118.  This  is  a  tank  made 
particularly  for  such  a  location.  The  cold  water  enters  at  the 
bottom  of  the  tank  and  also  leaves  the  bottom  on  its  way 
to  the  water-back.  Circulation  takes  place  through  the  water- 
-back  as  before  but  when  hot  water  is  drawn  from  the  top  of 
the  tank,  the  entering  cold  water  at  the  bottom  mixes  with  only 
that  at  the  lower  part  of  the  tank  and  so  cools  but  a  small 
amount  of  the  hot  water  in  storage.  Hot- water  tanks  of  this 
kind  are  tapped  for  pipe  connections  in  two  places  on  both  the  top 
and  bottom  sides  and  also  at  the  ends  as  shown  in  the  drawing. 


PLUMBING 


121 


Tank  Heaters. — When  the  demand  for  hot  water  is  sufficient 
to  warrant  a  separate  hot-water  heater  the  apparatus  similar 
to  Fig.  119  is  used.  With  such  a  heater,  the  conditions  of  over- 
heated water — to  be  described  later — may  be  almost  entirely 
avoided.  In  this  case  the  connections  are  arranged  similarly  to 
those  of  the  range  boiler  but  a  separate  furnace  takes  the  place 
of  the  water-back.  The  heater  is  simply  a  small  furnace  made 
expressly  for  heating  water.  Connected  with  the  discharge  pipe 
p  is  a  draft-regulating  valve  which  controls  the  drafts  of  the 
heater.  The  draft-regulator  is  set  to  so  con- 
trol the  furnace  that  water  at  the  desired 
temperature  will  always  be  in  the  tank. 
The  mechanism  of  this  regulator  is  the  same 
as  the  draft-regulator  described  under  hot- 
water  heating  plants. 

Overheated  Water. — Under  ordinary  con- 
ditions the  water  contained  in  the  range 
boiler  is  below  the  atmospheric  boiling  point 
(212°F.)  but  at  times  when  a  hot  fire  is  kept 
up  in  the  range  for  a  considerable  period,  the 
temperature  will  rise  to  a  degree  much  above 
that  amount.  The  temperature  to  which 
the  water  will  rise  will  depend  on  the  pres- 
sure of  the  water  supply.  As  an  example  FlG  119.— indepen- 

— Suppose    the    gage    pressure    Of    the    Water   dent   hot-water    heater 

with  temperature  regu- 

supply  is  25  pounds.     The  temperature  cor-  lator 
responding  to  that  pressure  is  258°F.     The 
temperature  of  the  water  in  the  tank  will  rise  to  that  amount 
but  not  further  because  any  additional  temperature  will  produce 
a  higher  pressure,  but  a  higher  pressure  would  be  greater  than  the 
pressure  of  the  water  supply  and  hence  will  back  the  water  into 
the  supply  pipe.     This  condition  of  things,  then,  acts  as  a  safety 
valve  to  the  tank  to  prevent  excessive  pressures. 

When  the  water  at  a  high  temperature  is  drawn  from  the  tap  a 
considerable  part  of  it  will  instantly  vaporize,  because  of  the 
reduced  pressure.  If  water  at  a  pressure  of  25  pounds  is  drawn 
from  the  faucet,  the  temperature,  258°F.,  is  sufficient  to  send  all 
of  the  water  instantly  into  steam.  This  high  temperature  will 
scald  at  the  slightest  touch.  The  water  drawn  from  the  faucet 


122 


MECHANICS  OF  THE  HOUSEHOLD 


will  continue  to  vaporize  as  it  comes  into  the  air  until  the  water 
in  the  tank  is  cooled  by  the  incoming  cold  water.  The  only 
means  of  relieving  the  overheated  condition  is  to  open  the  faucet 
a  slight  amount  and  allow  a  portion  of  the  heated  water  to  be 
drawn  off. 

It  is  evident  from  what  has  been  said  of  the  range  boiler  that 
it  operates  under  a  variety  of  condi- 
tions. It  is  first  a  storage  tank  in 
which  is  accumulated  the  water,  heated 
from  a  greater  or  less  period  of  use  of 
the  range.  Should  the  range  fire  be 
maintained  through  the  day  or  night 
the  supply  of  hot  water  will  be  excessive 
and  superheating  is  the  result.  If  the 
heater  is  to  be  used  during  short  periods 
of  time,  the  piping  should  be  arranged 
to  produce  the  best  circulation;  on  the 
contrary,  should  the  heater  be  used  con- 
tinuously— as  in  the  case  of  a  furnace 
coil — a  slow  circulation  through  the 
tank  is  most  to  be  desired  and  the 
piping  should  be  arranged  for  that 
purpose. 

In  the  use  of  furnace  heaters,  super- 
heating is  likely  to  occur  during  cold 
weather  when  a  hot  fire  must  be  used 
over  a  long  period  of  time.     In  order 
to  conserve  the  heat  accumulated  under 
such    conditions  a  hot-water  radiator 
is  frequently  connected  with  the  range 
boiler  through  which  to  dispose  of  the 
FIG.  120. — The  range  boiler  excess   heat.     This    radiator    may    be 
connections  when  a  furnace  piaced  in  any  desired  position  and  so 

coil  is  used  for  hot-water  heat-  ... 

ing.  connected  by  a  valve  as  to  discontinue 

its  use  at  any  time. 

Furnace  Hot- water  Heaters. — It  is  sometimes  more  con- 
venient to  use  the  furnace  as  a  means  of  heating  water  than  the 
kitchen  range.  Such  an  arrangement  is  shown  in  Fig.  120, 
where  a  loop  of  pipe  in  the  fire-box  of  the  furnace  takes  the  place 


PLUMBING  123 

of  the  water-back.  The  arrangement  of  the  pipes  in  the  range 
boiler  are  as  before,  the  water  entering  the  tank  through  the 
pipe  A,  circulates  through  the  pipes  B  and  C,  receiving  its  heat 
while  passing  through  the  loop  in  the  furnace,  in  exactly  the 
same  way  as  in  the  water-back.  It  would  be  quite  possible  to 
also  connect  the  kitchen  range  with  the  tank  as  shown  by  the 
dotted  lines  indicating  the  water-back.  Such  an  arrangement 
would  virtually  be  that  shown  in  Fig.  116,  where  the  two  heaters 
on  different  floors  are  connected  with  the  boiler. 

Instantaneous  Heaters. — In  isolated  bathrooms  where  no  con- 
stant supply  of  hot  water  is  available,  instantaneous  hot- water 
heaters  are  much  used.  In  many  houses  where  a  range  fire  is 
used  intermittently,  particularly  during  the  summer  months, 
a  like  method  is  used  for  the  hot-water  supply.  These  heaters 
are  made  in  many  forms  to  suit  any  condition.  Some  are  very 
simple,  being  made  of  a  gas  heater,  the  heat  from  which  is  held 
against  a  long  coil  of  pipe  or  a  large  amount  of  heating  surface 
in  other  form,  through  which  the  water  circulates  on  its  way 
to  the  tap.  Others  are  quite  elaborate,  being  made  entirely 
automatic  in  their  action.  The  Ruud  heater,  for  example,  is 
so  constructed  that  when  the  hot-water  faucet  is  opened  the 
reduced  water  pressure  starts  a  gas  heater  in  contact  with  a 
series  of  pipe  coils  through  which  the  water  circulates.  As  soon 
as  the  water  faucet  is  closed  the  water  pressure  automatically 
closes  the  gas  valve,  cutting  off  the  supply  of  gas.  A  little  gas 
jet  used  for  igniting  the  burner  is  left  constantly  burning,  ready 
to  light  the  gas  whenever  hot  water  is  required. 

Fig.  121  illustrates  a  simple  form  of  instantaneous  heater  that 
is  relatively  inexpensive  and  has  met  with  a  great  deal  of  favor. 
A  sheet-iron  casing  encloses  a  sinuous,  multiple  coil  of  pipes 
through  which  the  water  passes.  The  heat  furnished  by  a  Bun- 
sen  burner  of  a  large  number  of  small  jets  is  evenly  distributed 
over  the  bottom  of  the  heater.  The  heating  coils  are  arranged  to 
interrupt  the  heat  passing  through  the  casing  and  absorb  as 
much  as  possible.  To  do  good  work  such  a  heater  must  be 
connected  by  a  pipe  to  a  chimney  flue  which  furnishes  a  good 
draught. 

Instantaneous  water  heaters  should  not  be  used  in  bathrooms 
unless  the  products  of  combustion  from  the  heater  are  carried 


124 


MECHANICS  OF  THE  HOUSEHOLD 


away  by  a  chimney.  The  combustion  of  the  required  amount 
of  gas  produces  a  large  volume  of  carbonic  acid  gas  which  if 
allowed  to  remain  in  the  room  is  not  only  deleterious  but  may  be 
a  positive  danger  to  life.  Cases  of  asphyxiation  from  this  cause 
are  not  at  all  rare. 


Discharge 


Chimuey 


FIG.   121. — Gas  heater  for  hot- 
water  supply. 


FIG.  122. — Hot-water  supply  with 
gas  heater,  connected  to  the  range 
boiler. 


Fig.  122  shows  the  heater  connected  with  a  range  boiler. 
In  this  case  the  heater  may  be  considered  as  taking  the  place 
of  the  water-back.  It  may,  however,  be  used  as  an  auxiliary 
heater.  In  the  picture  of  the  kitchen  shown  in  Fig.  80,  an 
instantaneous  heater  is  shown  attached  to  the  range  boiler. 
It  is  located  in  this  case  between  the  kitchen  range  and  the 
boiler. 


CHAPTER  VII 
WATER  SUPPLY 

The  use  of  water  enters  into  each  detail  of  the  affairs  of 
everyday  life  and  forms  a  part  of  every  article  of  food;  its 
quality  has  much  to  do  with  the  health  of  the  family,  and  its 
convenience  of  distribution  lends  greatly  to  the  contentment  of 
its  members.  The  family  water  supply  should  be  as  carefully 
guarded  as  means  will  permit,  and  judicious  care  should  be 
exercised  to  prevent  the  possibility  of  its  pollution.  Where 
the  source  of  the  water  is  known,  it  should  be  the  subject  of 
unremitting  attention. 

Water  comes  originally  from  rain  or  snow  and  as  it  falls,  it 
is  pure.  Water,  however,  in  falling  through  the  air  absorbs  the 
contained  vapors  and  washes  the  air  free  from  suspended  organic 
matter  in  the  form  of  dust,  so  that  when  it  reaches  the  earth 
rain  water  contains  some  impurities. 

As  the  water  is  absorbed  by  the  earth,  it  comes  into  contact 
with  the  mineral  matter  and  organic  materials  of  animal  and 
vegetable  origin  contained  in  the  soil;  and  as  water  is  a  most 
wonderful  solvent,  it  soon  contains  mineral  salts  and  possibly 
the  teachings  from  the  organic  substances  through  which  it 
passes.  The  impurities  usually  found  in  well  water  are  in  the 
form  of  mineral  salts  that  have  been  taken  up  from  the  earth, 
but  other  contaminating  materials  may  come  from  the  surface 
and  be  carried  into  the  well  by  accidental  drainage. 

Water  that  is  colorless  and  odorless  is  usually  considered  good 
for  drinking  and  in  the  absence  of  more  accurate  means  of 
determination  may  be  used  as  a  test  of  excellence;  but  it  often 
happens  that  water  possessing  these  qualities  is  so  heavily 
freighted  with  mineral  salts  as  to  be  the  direct  cause  of  impaired 
health.  Again,  water  that  appears  pure  may  be  polluted  with 
disease-producing  bacteria  to  such  an  extent  as  to  endanger 
the  Jives  of  all  who  use  it.  The  fact  that  a  source  of  drinking 

125 


126  MECHANICS  OF  THE  HOUSEHOLD 

water  bears  a  local  reputation  for  purity,  because  of  long  usage, 
cannot  be  taken  as  a  test  of  its  actual  purity  until  it  has  been 
subjected  to  chemical  and  bacterial  examination. 

It  must  not  be  inferred  that  all  water  is  likely  to  be  unsuitable 
for  drinking;  there  is,  however,  a  possibility  of  the  water  being 
polluted  from  natural  sources  and  from  accidental  causes,  that 
are  sometimes  preventable;  and  the  only  means  of  determining 
the  purity  of  water  is  by  chemical  and  bacterial  examining. 

Water  Analysis. — In  order  to  be  assured  as  to  the  quality  of 
drinking  water,  it  should  be  subjected  to  analysis  and  the  result 
of  the  analysis  inspected  by  a  physician  of  good  standing.  Such 
analysis  may  usually  be  obtained  free  of  charge  from  the  State 
Board  of  Health  and  if  asked,  the  Chief  Chemist  will  usually  give 
his  opinion  regarding  the  quality  as  drinking  water. 

In  chemical  water  analysis,  the  total  amount  of  solids,  regard- 
less of  their  nature  is  taken  as  indicative  of  its  excellence  for 
drinking  purposes.  These  solids  may  be  either  in  suspension 
and  give  the  water  a  color  or  produce  a  turbidity,  or  they  may 
be  entirely  in  solution  and  the  water  appear  colorless.  English 
authorities  on  the  subject  place  the  allowable  proportion  of 
solids  at  500  parts  to  the  million.  Any  water  that  contains 
more  than  500  parts  to  the  million  is  condemned  for  drinking 
purposes.  Water*  containing  500  parts  or  less  to  the  million 
is  considered  good.  The  Standard  of  the  American  Board  of 
Health  permits  the  use  of  water  for  city  supply  that  contains 
1000  parts  of  solid  matter  to  the  million. 

The  amount  of  solids  contained  in  water  is  not  at  all  a  definite 
indication  of  its  quality  for  drinking  purposes,  as  may  be  inferred 
from  the  widely  varying  amounts  permitted  by  the  different 
authorities,  but  it  gives  an  indication  of  its  character  because  of 
the  known  physiological  action  of  the  contained  solids. 

Chemical  analysis  alone  cannot  be  taken  as  a  complete  indica- 
tion of  the  character  of  water,  because  such  analysis  shows 
nothing  of  the  bacteria  that  may  be  present.  The  organic  matter 
may  indicate  the  possible  presence  of  bacteria,  but  microscopic 
examination  will  be  required  to  determine  its  harmful  properties. 

As  examples  of  the  chemical  constituents  of  potable  waters, 
the  following  furnish  illustrations  of  different  types  of  water  in 
general  use, 


WATER  SUPPLY  127 

Pokegama  Water. — The  water  from  Pokegama  Spring  at 
Detroit,  Minn,  is  used  widely  through  the  Northwest  as  a  table 
water.  It  is  considered  to  be  a  very  excellent  drinking  water 
because  of  the  low  amount  £>f  solids  and  the  absence  of  any 
deleterious  constituents.  The  complete  chemical  analysis  as  re- 
ported by  the  North  Dakota  Pure  Food  Laboratory  is  as  follows : 

Grains  per  gallon 

Sodium  chloride 0.0200 

Sodium  sulphate 0.0357 

Sodium  carbonate 3.9288 

Calcium  carbonate 11 . 3997 

Lime  carbonate 0 . 0016 

Magnesium  carbonate 3 . 8896 

Sodium  phosphate trace 

Potassium  sulphate 0 . 4435 

Silica 0.4416 

Organic  matter 0 . 1006 


Total 20.2611 

The  total  splids,  20.2611  grains  per  gallon,  equivalent  to  346.85 
parts  per  million,  is  very  low  and  composed  of  carbonates  of 
sodium,  calcium  and  magnesium,  none  of  which  are  in  any  way 
harmful  even  in  much  larger  quantities.  The  amount  of  organic 
matter  is  practically  nothing. 

River  Water. — The  water  supply  of  the  city  of  Fargo,  N.  D., 
is  taken  from  the  Red  River  of  the  North,  which  after  being 
filtered  through  a  mechanical  filtration  plant  is  supplied  to  the 
water  system  of  the  city.  The  river  water  in  its  raw  state  is 
considered  unfit  for  drinking  because  of  the  amount  of  organic 
matter  present  at  different  times  of  the  year. 

Analysis  of  raw  water  from  intake  pipe,  April  14,  1913: 

Parts  per  million 

Chlorine 10 

Equivalent  as  sodium  chloride,  salt 16 

Volatile  and  organic  matter 80 

Mineral  solids 180 

Total  solids ..         260 

In  this  water  neither  the  solids  nor  the  organic  matter  are  at 
all  high  but  during  a  part  of  each  year  there  are  many  pathogenic 


128  MECHANICS  OF  THE  HOUSEHOLD 

germs  present,  the  contained  typhoid  bacillus  being  the  most 
feared.  The  following  is  an  analysis  after  the  water  has  been 
filtered,  April  14,  1913: 

Parts  per  million 

Chlorine 12 

Equivalent  as  sodium  chloride,  salt 18 

Volatile  and  organic  matter 45 

Mineral  solids 140 

Total  solids 185 

It  will  be  noticed  that  in  the  process  of  filtration  there  has  been 
removed  from  the  water  35  parts  to  the  million  of  organic  matter 
and  with  probably  99  per  cent,  of  the  pathogenic  bacteria.  In 
addition  there  has  been  removed  40  parts  to  the  million  of  min- 
eral solids,  the  removal  of  which  has  changed  a  very  hard  water 
to  that  which  is  reasonably  soft.  The  process  of  filtration  has 
changed  water  that  is  generally  condemned  for  drinking  to  one 
that  is  considered  remarkably  good. 

Artesian  Water. — The  analysis  of  the  sample  of  artesian  water 
given  below  is  an  example  of  the  water  analysis  made  by  the 
North  Dakota  Pure  Food  Laboratory.  It  furnishes  an  illustra- 
tion of  the  type  of  reports  that  are  returned  from  samples  of 
water  submitted  for  examination.  This  report  was  in  the  form 
of  a  letter  which  was  taken  at  random  from  the  files  of  the 
laboratory. 

Sample  of  artesian  water  No.  1936  from  Moorhead,  Minn. : 

Parts  per  million 

Chlorine. 70 

Equivalent  as  sodium  chloride,  salt 116 

Volatile  and  organic  matter 90 

Mineral  solids. .  455 


Total  solids 545 

"The  solids  in  this  water  are  made  up  of  sodium  chloride,  salt,  116 
parts;  volatile  and  organic  matter,  90  parts;  lime  sulphate,  a  trace; 
lime  carbonate,  a  slight  amount;  magnesium  carbonate,  a  slight  amount; 
and  the  balance  of  the  solids  are  all  wholly  made  up  of  sodium  bicar- 
bonate. This  water  is  low  in  solids  and  of  good  quality." 

Medical  Water. — The  solids  that  occur  most  commonly  in 
spring  and  well  water  appear  in  the  form  of  mineral  salts.  It 


WATER  SUPPLY  129 


frequently  happens  that  salts  giving  a  cathartic  action  are  pres- 
ent in  sufficient  quantity  to  render  the  water  objectionable  when 
used  for  drinking.  Sodium  chloride  or  common  salt  frequently 
occurs  in  quantity  sufficient  to  be  distinctly  noticeable.  Mag- 
nesium sulphate  (Epsom  salts)  and  sodium  sulphate  (Glauber 
salts),  both  of  which  are  well-known  laxative  salts,  very  commonly 
occur  in  well  water.  The  carbonates  of  calcium  and  sulphur 
also  frequently  found  in  well  water  are  inert  in  physical  action 
when  taken  in  drinking  water.  The  presence  of  laxative  salts 
in  spring  water  has  given  great  celebrity  to  many  springs  both 
in  Europe  and  America  that  are  famous  as  cures  for  all  manner 
of  human  ills.  Such  curative  value  as  these  springs  possess  is 
derived  from  the  cathartic  salts  contained  by  the  water. 

The  table  of  contents  of  the  Saratoga  Congress  Water  as  given 
by  Dr.  Woods  Hutchinson  shows  the  solids  of  one  of  the  most 
celebrated  of  America's  medicinal  waters. 

Grains  per  gallon 

Sodium  chloride 385 

Magnesium  carbonate 56 

Calcium  carbonate  and  sulphate .116 

Sodium  bicarbonate 9 

Sodium  iodide 4 

Bromide,  iron,  silica trace 


Total  solids 570 

When  reduced  to  ordinary  measure  and  given  their  com- 
mon names  the  mineral  solids  in  a  gallon  of  this  water  will  be 
approximately: 

Common  salt 8  teaspoonfuls 

Magnesium 1  teaspoonful 

Lime  and  plaster  of  Paris 2  teaspoonfuls 

Baking  soda y%  teaspoonful 

Bromides  and  iodides }{2  teaspoonful 

The  total  solids,  570  grains  per  gallon,  contained  in  Saratoga 
water,  gives  the  remarkably  high  content  in  total  solids,  of  9758 
parts  per  million;  this  is  almost  ten  times  the  limit  of  the  Ameri- 
can standard.  While  such  water  would  not  do  for  constant  con- 
sumption, it  is  taken  for  considerable  periods  of  time  with  benefi- 
cial results  and  is  recommended  by  many  authorities  as  a  water 
of  great  medicinal  potency. 


130  MECHANICS  OF  THE  HOUSEHOLD 

While  most  medical  authorities  condemn  the  use  of  water  high 
in  solids,  the  ideal  drinking  water  is  neither  soft  water  nor 
distilled  water — that  is,  water  that  is  perfectly  free  from  any! 
saltiness — but  one  that  contains  a  moderate  amount  of  the  ordi- : 
nary  constituents  of  the  earth.  It  is  reasonably  safe  to  assume 
that  any  unpolluted  water  containing  as  high  percentage  of  solids 
as  1000  parts  of  total  solids  to  the  million,  and  that  is  agreeable 
to  the  taste,  would  be  safe  for  drinking. 

"Chemical  analysis  in  general  indicates  the  possible  pollution  of 
water.  A  relatively  high  content  of  organic  substances,  nitrate, 
chlorides  and  sulphates,  might  indicate  contamination,  particularly 
when  ammonia  is  also  present.  On  the  other  hand,  a  high  content 
of  just  one  of  the  above-mentioned  substances,  be  it  organic,  chloride, 
nitrate  or  sulphate,  may  originate  from  the  natural  soil  strata." 

Organic  Matter. — Organic  matter  may  come  from  peat 
swamps,  decaying  leaves  and  grasses;  or  it  may  come  from 
decayed  animal  matter  which  finds  its  way  into  the  soil;  or 
worst  of  all  it  may  come  from  cesspools  or  other  sewage.  While 
the  presence  of  organic  matter  does  not  necessarily  indicate  the 
presence  of  disease-producing  bacteria,  it  is  a  medium  in  which 
such  germs  live  and  multiply;  for  that  reason  it  is  an  indicator 
of  possible  harm. 

"  Waters  containing  a  high  percentage  of  organic  substances  and 
among  them  products  of  putrefaction  are  frequently  used  without 
damage  but  they  are  capable  of  producing  gastro-intestinal  catarrh, 
phenomena  of  excitement  and  paralysis  as  well  as  death.  Of  the  many 
pathogenic  bacteria  that  sooner  or  later  may  get  into  the  water,  those  of 
cholera  and  typhoid  are  of  special  importance. 

"  Pathogenic  bacteria  occur  but  rarely  and  when  once  they  find  their 
way  into  a  water,  they  generally  do  not  multiply  but  remain  for  a  greater 
or  lesser  period  viable. 

" Bacteria  enter  wells  by  three  different  modes:  first,  from  surface 
water  that  is  washed  from  the  soil  by  rain;  second,  from  faulty  construc- 
tion of  the  curbing;  and  third,  from  bacteria  entering  the  soil  from  vaults, 
etc."  (Van  Es). 

Ammonia. — In  the  analysis  of  water  the  presence  of  ammonia 
is  an  indicator  of  organic  matter.  Ammonia  is  not  of  itself 
injurious  but  it  indicates  the  presence  of  matter  in  which  bacteria 


WATER  SUPPLY  131 

find  conditions  suited  to  their  growth.  Free  ammonia  is  usually 
considered  an  indicator  of  recent  pollution,  while  albuminoid 
ammonia  indicates  the  presence  of  nitrogenous  matter  that 
has  not  undergone  sufficient  decomposition  to  form  ammonia 
compounds. 

Hardness  in  Water. — Water  that  holds  no  mineral  matter  in 
solution  is  "soft  water"  and  when  soap  is  added  will  readily  form  a 
lather.  The  presence  of  lime  or  magnesia  is  commonly  the  cause 
of  "hardness"  in  water.  Either  of  these  minerals,  when  pres- 
ent form  an  insoluble  curd  when  the  soap  is  added  to  the  water 
and  the  soap  will  not  form  a  lather  until  enough  soap  has  been 
added  to  unite  with  the  mineral  matter  present.  The  hardening 
agents  are  usually  in  the  form  of  bicarbonates  and  sulphates. 
All  soap  used  in  neutralizing  the  hardening  agents  is  wasted, 
because  a  lather  will  not  form  until  all  of  the  hardening  materials 
are  neutralized.  It  is  evident  that  the  softening  of  water  for 
domestic  purposes  is  beneficial,  both  because  of  the  less  amount 
of  soap  required  and  because  of  the  absence  of  the  curd. 

Hardness  in  water  may  occur  in  two  forms — as  temporary 
hardness  or  as  permanent  hardness.  When  bicarbonate  predomi- 
nates as  the  hardening  agent,  the  water  is  said  to  be  temporarily 
hard  because,  when  heated  to  boiling,  the  bicarbonate  is  precipi- 
tated and  the  water  is  thus  softened.  When  softening  of  such 
water  is  to  be  done  on  a  large  scale,  chemical  treatment  is 
more  satisfactory.  Water  containing  bicarbonate  of  lime  may 
be  softened  by  adding  a  pound  of  lime  to  1000  gallons  or  1  pound 
of  lime  to  165  cubic  feet  of  the  water.  This  quantity  of  lime 
is  sufficient  to  remove  10  grains  of  the  bicarbonate  to  the  gallon. 

When  the  mineral  matter  is  in  the  form  of  sulphates,  mainly 
sulphate  of  lime  or  magnesia,  the  water  is  said  to  be  permanently 
hard,  because  boiling  will  not  soften  it.  Such  water  may  be 
softened  by  adding  sjoda  ash  or  impure  carbo>najte__of,§oila.  One 
pound  to  1J4  pounds  of  "washing  soda'7  to  each  1000  gallons 
of  water  will  render  such  water  soft;  by  its  action  the  sulphate 
of  lime  is  precipitated  and  settles  to  the  bottom  of  the  container; 
the  water  may  then  be  siphoned  off  leaving  the  precipitate  in 
the  bottom. 

Iron  in  Water. — Water  containing  iron  is  found  in  many  wells 
and  springs.  While  iron  is  not  harmful,  it  is  objectionable  to 


132  MECHANICS  OF  THE  HOUSEHOLD 

taste  and  stains  most  things  with  which  it  is  long  in  contact. 
It  may  be  precipitated  with  lime  and  removed  as  the  sulphate 
of  magnesia  described  in  the  preceding  paragraph. 

Water  Softening  with  Hydrated  Silicates. — By  W.  L.  Stock- 
ham,  assistant  chemist,  North  Dakota  Experiment  Station. 

"The  use  of  chemicals  in  softening  water  requires  the  mechanical 
removal  of  the  separated  materials  by  skimming,  settling  or  filtering 
and  it  is  difficult  to  determine  just  how  much  chemical  to  add.  A  new 
process  for  softening  water,  and  one  that  has  awakened  great  interest 
because  of  its  efficiency,  employs  hydrated  silicates  of  aluminum  or 
iron  combined  with  soluble  bases.  This  process  softens  water  from 
practically  any  condition  or  hardness. 

"The  form  of  apparatus  in  use  varies  from  a  portable  jar,  with  an 
inlet  at  the  top  and  an  outlet  at  the  bottom,  to  the  more  complex 
tanks  for  industrial  and  domestic  purposes.  A  plant  for  domestic 
use  might  consist  of  a  20-gallon  tank  for  containing  the  softening  mate- 
rial and  a  second  tank  in  which  is  prep'ared  the  salt  solution  for  reacti- 
vating the  softener.  The  two  tanks  with  their  valves  and  connections 
constitute  the  apparatus.  The  softener,  supported  by  a  porous  plate, 
sieve,  or  layer  of  gravel,  completely  fills  the  first  tank  and  the  water 
to  be  treated  passes  through  the  interspaces  between  the  granules. 
In  some  plants  the  water  passes  through  a  layer  of  marble  chips  before 
coming  into  contact  with  the  softener.  The  apparatus  may  be  attached 
temporarily  to  the  faucet  or  connected  permanently  with  the  water 
system.  A  gravity  system  may  be  employed  where  the  water  pressure 
is  lacking. 

"The  softener  is  put  on  the  market  in  granular  form  and  may  be 
purchased  and  used  with  apparatus  other  than  that  furnished  by  manu- 
facturers. The  granules  are  about  %  inch  in  diameter  and  permit 
a  ready  passage  of  the  water  through  the  interspaces.  The  material 
lasts  indefinitely. 

"As  the  water  passes  through  the  apparatus,  the  large  exposed 
surface  of  the  granules  entirely  absorbs  the  calcium  and  magnesium, 
which  produce  hardness,  making  it  soft  and  ready  for  immediate 
use.  The  water  does  not  require  being  in  contact  with  the  softener 
any  longer  than  the  time  taken  to  pass  through  and  it  emerges  almost 
as  fast  as  from  the  faucet.  The  softener  must  be  reactivated  after 
it  has  softened  a  certain  amount  of  water.  This  is  accomplished  by 
filling  the  tank  with  a  common  salt  solution  which  is  contained  in  the 
second  tank.  The  water  supply  is  temporarily  shut  off  and  the  salt 
solution  allowed  to  fill  the  softening  tank.  After  remaining  in  contact 


WATER  SUPPLY  133 

with  the  granules  for  a  time  the  chemicaLaction  of  the  salt  releases  the 
calcium  and  magnesium,  which  are  flushed  out  with  the  excess  of  salt 
solution,  into  the  sewer.  The  softener  thus  renewed  is  ready  for  soften- 
ing another  supply  of  water.  Since  this  renewal  is  a  simple  application 
of  the  law  of  mass  action,  an  excess  of  the  salt  must  be  used.  The 
renewal  may  be  repeated  indefinitely. 

The  amount  of  any  particular  sample  of  water  which  can  be  softened 
before  renewal  depends  on  the  amount  of  material  in  the  apparatus 
and  the  hardness  of  the  water.  Five  gallons  of  the  water  per  pound 
of  softener  would  not  be  far  from  the  average  capacity.  Where  a 
large  amount  of  soft  water  is  required  at  one  time,  it  may  be  prepared 
in  advance  and  accumulated  in  a  tank  or  cistern. 

"The  cost  of  softening,  aside  from  the  original  cost  of  the  plant,  is 
nominal,  as  the  value  of  the  salt  solution  is  the  only  expense. 

"The  water  produced  by  this  process  is  absolutely  soft  and  suitable 
for  drinking,  domestic  and  industrial  purposes.  In  the  case  of  very 
hard  water  the  saving  in  soap  for  washing  is  more  than  equal  to  the 
cost  of  operation.  There  are  at  least  three  firms  manufacturing  soften- 
ing plants  of  the  kind  at  the  present  time:  The  Permutite  Co.  of  New 
York;  the  Cartright  Co.  of  Chicago,  whose  product  is  called  Borromite; 
and  the  Des  Moines  Refining  Co.,  manufacturers  of  Refinite. 

"A  comparative  test  of  various  forms  of  water-softening  materials 
may  be  obtained  from  the  Regulatory  Department,  North  Dakota 
Agricultural  College."  . 

Chlorine. — The  presence  of  chlorine  in  water  may  indicate 
the  presence  of  polluting  matter  in  the  form  of  sewage  but  only 
when  the  amount  is  considerably  above  the  normal  amount  of 
chlorine  that  is  contained  in  the  soil  in  the  community  from 
which  the  water  is  taken.  An  increase  of  the  chlorine  in  the 
water  would  indicate  a  probable  pollution  from  sewage. 

Polluted  Water.— Well  water  that  is  roily  or  that  possesses  ob- 
jectionable taste  or  odor  may  be  suspected  of  containing  pol- 
luting matter  and  should  be  boiled  before  being  used  for  drinking 
por poses  until  such  time  as  may  be  required  to  have  it  examined. 
Sickness  due  to  the  use  of  polluted  water  does  not  necessarily 
develop  as  specific  diseases,  unless  the  water  contains  disease- pro- 
ducing bacteria.  Typhoid  fever,  one  of  the  commonest  and  most 
dreaded  of  diseases,  is  usually  transmitted  by  water.  Typhoid 
is  a  disease  of  human  origin,  the  germ  of  which  develops  in 
the  elementary  tract  of  the  human  kind  alone.  The  germs  may 


134 


MECHANICS  OF  THE  HOUSEHOLD 


be  spread  by  the  waste  from  the  typhoid  patient  by  being  thrown 
on  the  ground  where  it  is  taken  up  by  the  water  and  passes  into 
streams  or  it  may  enter  wells  from  privies  or  cesspools.  A 
single  case  of  typhoid  has  been  known  to  so  pollute  the  water  of  a 
stream,  as  to  produce  an  epidemic  of  the  disease  throughout  the 
entire  length  of  the  stream,  among  the  people  who  drank  its 
water;  while  water  from  a  polluted  well  often  transmits  disease 
to  a  neighborhood. 

Pollution  of  Wells. — The  water  from  wells  is  often  polluted 
by  seepage  through  the  earth  from  sources  that  might  be  pre- 
vented. Fig.  123  illustrates  some  of  the  commonest  sources  of 
contamination  that  through  carelessness  or  ignorance  are  located 
in  the  neighborhood  of  the  family  water  supply.  The  drainage 


FIG.  123. — Some  of  the  common  causes  of  pollution  of  wells,  and  the  means  of 
transmitting  disease,  such  as  typhoid,  etc. 

from  such  sources  of  pollution  is  often  directed  toward  the  well 
and  many  cases  of  ill-health,  disease  or  death  are  the  direct 
consequences  of  drinking  its  water.  It  may  be  readily  observed, 
in  the  case  of  the  well  illustrated,  that  the  more  water  that  is 
pumped  from  the  well,  the  greater  will  be  the  tendency  of  the 
water  from  each  of  the  sources  of  pollution  to  reach  the  well. 

Another  common  cause  of  contamination  of  well  water  is  that 
of  imperfect  well  curbs  that  allow  the  waste  water  or  surface 
water  to  flow  into  the  well.  The  area  about  the  well  should  be 
graded  to  allow  no  standing  water,  and  the  waste  should  be  con- 
ducted away  without  permitting  it  to  collect  in  standing  pools. 

Drainage  from  manured  fields  or  other  places  where  disinte- 
grating animal  or  vegetable  matter  may  be  absorbed  by  water  is 


WATER  SUPPLY  135 

often  the  cause  of  temporary  pollution,  where  the  water  is  carried 
to  low-lying  wells.     Wells  located  in  low  areas  that  receive  the 
drainage  from  such  places  may  be  suspected  of  pollution  during 
the  spring  or  early  summer,  when  during  the  remainder  of  the ' 
year  the  water  is  pure. 

In  connection  with  any  water  suspected  of  pollution,  it  is  well 
to  remember  that  by  boiling  the  water  used  for  drinking,  its 
harmful  properties  are  entirely  destroyed. 

Safe  Distance  in  the  Location  of  Wells. — In  the  location  of  a 
well,  the  distance  of  safety  from  sources  of  pollution  will  depend, 
in  a  considerable  measure,  on  the  character  of  the  soil  and  the 
quantity  and  concentration  of  the  pollution  material  entering 
the  ground  water.  When  coming  from  the  surface,  the  danger 
is  usually  neither  great  nor  difficult  to  avoid ;  but  when  cesspools 
and  privies  in  the  neighborhood  are  sunk  to  a  considerable  depth 
in  porous  earth,  from  which  the  supply  of  water  is  drawn,  the 
polluting  material  may  reach  the  well  undiluted.  No  absolute 
radius  of  safety  can  be  given,  but  certain  generalizations  as  to 
conditions  may  be  made  as  to  character  of  soil  and  the  different 
topographical  conditions  which  surround  a  safe  location. 

In  ordinary  clay,  or  in  clay  mixed  with  pebbles  and  in  soils  of 
the  same  general  nature,  through  which  the  water  circulates  by 
seepage,  the  pollution  is  not  likely  to  be  carried  to  a  distance  of 
100  feet.  Clay  offers  marked  resistance  to  the  passage  of  water, 
which  in  beds  of  3  to  5  feet  thick  will  act  as  protection  from  pollu- 
tion from  above.  In  sandy  soils  the  movement  of  water  is  faster 
than  in  clayey  soils,  but  150  feet  may  be  taken  as  a  safe  distance, 
unless  the  downward  slope  of  the  land  carries  the  polluting  ma- 
terial directly  to  the  well. 

Surface  Pollution  of  Wells. — In  dug  wells,  pollution  from  the 
surface  is  due  most  commonly  to  careless  construction  and  lack 
of  care.  In  Fig.  124  is  indicated  the  most  common  cause  of 
surface  pollution.  The  figure  represents  a  well  that  has  been 
curbed  with  planks.  Through  lack  of  care  the  earth  has  sunken 
at  the  top,  permitting  the  surface  water  to  flow  into  the  well. 
The  top  of  the  well  is  on  a  level  with  the  surface  and  covered 
with  loosely  laid  boards  which  allow  the  waste  water  to  drip 
through  the  joints.  Such  a  well,  even  though  the  source  of 
supply  is  good,  will  likely  yield  water  of  inferior  quality. 


136 


MECHANICS  OF  THE  HOUSEHOLD 


In  bored-  wells,  polluting  water  may  enter  through  the  unce- 
mented  joints  of  the  tiling  or  through  the  joints  in  the  staves  of 
wooden  tubing;  in  drilled  or  driven  wells,  through  leaky  joints 
or  holes  eaten  in  the  iron  casing  by  corrosive  waters.  By  ce- 
menting the  interior  surface  of  stone-  or  brick-curbed  wells,  by 
replacing  wood  with  cement  or  other  impervious  curbs  and 
by  substituting  new  pipes  for  leaky  iron  casings,  the  entrance 
of  polluting  water  may  be  prevented. 

In  the  average  home  the  water  supply  is  most  commonly 
taken  from  a  well,  the  water  from  which  comes  through  the 

earth  from  unknown  sources,  and 
the  character  of  chemical  salts 
or  organic  matter  the  water  con- 
tains will  depend  on  the  kind  of 
soil  through  which  it  passes  before 
reaching  the  well. 

The  water  from  wells,  whether 
deep  or  shallow,  is  generally  of 
relatively  local  origin,  it  being  ab- 
sorbed by  the  soil  and  carried  to 
the  water  stratum  by  percolation. 
If  the  soil  contains  soluble  min- 
eral salts  the  water  will  contain 
these  materials  in  quantities  de- 
pending on  the  amount  of  the 
salts  present  in  the  earth.  If 
the  earth  contains  organic  matter 
as  pathogenic  bacteria  the  water 

is  likely  to  contain  these  bacteria  in  like  numbers  as  they  are 
present  in  the  soil  through  which  the  water  niters. 

As  usually  encountered,  the  water-bearing  earth  occurs  in 
sheets  rather  than  in  veins  or  streams.  The  movement  of  the 
water  in  such  areas  follows  the  contour  of  the  earth  and  is 
influenced  by  the  varying  amount  of  rain  or  snowfall  and  the 
atmospheric  pressure.  The  lateral  movement  is  often  only  a 
few  inches  a  day  and  in  some  places  no  lateral  movement  occurs 
at  all.  Underground  streams  of  any  kind  are  not  usually  found 
except  in  limestone  regions. 

As  a  rule,  a  well  is  formed  by  digging  or  boring  into  the  earth 


FIG.   124. — Undesirable  form  of 
well  curbing. 


WATER  SUPPLY  137 

until  a  stratum  of  water-bearing  soil  is  encountered,  the  type  of 
the  well  being  determined  by  the  character  of  the  earth  and  the 
location  of  the  water-bearing  soil.  The  water  from  the  surround- 
ing area  fills  the  opening  to  the  height  of  the  saturated  soil. 
As  the  water  is  pumped  from  the  well  it  is  replenished  by  the  flow 
from  the  surrounding  earth.  If  the  soil  is  porous,  as  in  the  case 
of  gravel,  the  water  will  refill  the  well  almost  as  fast  as  it  is  taken 
away  by  the  pump.  If  the  soil  is  dense  and  the  inward  flow  is 
slow,  the  well  when  once  exhausted  may  be  a  long  time  in  refilling. 

Water  Table. — The  upper  level  of  the  saturated  portion  of 
the  soil  is  known  as  the  water  table.  It  has  a  definite  surface 
that  conforms  to  the  broader  surface  irregularities.  While  a 
definite,  determinable  water  table  appears  only  in  porous  soil, 
it  exists  even  in  dense  rocks.  It  rises  and  falls  in  wet  seasons 
and  in  drought.  In  exceptionally  wef  seasons  the  water  table 
may  be  at  or  above  the  surface.  Under  such  conditions  the  op- 
portunities for  the  pollution  of  wells  is  much  increased.  In 
particularly  dry  seasons  the  water  table  may  sink  below  the 
bottom  of  the  well,  when  it  is  said  to  "go  dry."  The  water 
table  follows  the  surface  contour  in  a  manner  depending  on  the 
character  of  the  soil.  It  is  flatest  in  sand  or  gravel  areas  but  in 
clay  it  follows  the  contour  of  deep  slopes  with  but  slight  variation. 

The  Devining  Rod.— The  use  of  the  devining  rod,  for  the 
purpose  of  locating  suitable  sites  for  wells,  has  been  supposed  by 
many  to  be  a  gift  possessed  by  a  chosen  few.  The  devining  rod 
is  a  forked  branch  of  witch  hazel,  peach  or  other  wood,  which 
when  held  in  the  hands  and  carried  over  the  ground,  is  supposed 
to  indicate  the  presence  of  water  by  bending  toward  it. 

In  most  cases  the  operators  are  entirely  honest  in  their  belief 
and  in  a  large  proportion  of  trial  their  efforts  have  been  successful 
in  locating  desirable  wells;  but  it  has  many  times  been  proven 
that  the  movement  of  the  rod  is  due  to  an  unconscious  muscular 
movement  of  the  arms  and  hands,  in  places  where  the  operator 
has  previously  suspected  the  presence  of  water.  The  operator 
of  the  devining  rods  is  most  successful  in  regions  where  water 
occurs  in  sheets,  such  as  often  occur  in  gravel  or  pebbly  clay. 
The  successful  use  of  the  devining  rod  cannot  be  explained  by 
any  scientific  reasons.  There  have  been  invented  a  number 
of  devining  rods,  claimed  by  their  inventors  to  be  based  on 


138  MECHANICS  OF  THE  HOUSEHOLD 

scientific  laws;  but  the  government  has  not  yet  granted  patents 
to  appliances  of  the  kind. 

Selection  of  a  Type  of  Well. — The  chief  factor  which  controls 
the  selection  of  a  type  of  well  is  the  nature  of  the  water-bearing 
earth,  the  amount  of  water  required,  the  cost  of  construction 
and  the  care  of  the  resulting  supply. 

If  a  large  amount  of  water  is  to  be  demanded  of  a  well,  to  be 
dug  in  soil  through  which  the  water  percolates  slowly,  the  well 
must  be  large  in  diameter,  in  order  that  the  necessary  supply  may 
be  accumulated.  If  the  earth  is  porous  and  yields  its  water 
readily,  a  small  iron  pipe  driven  into  the  ground  may  supply 
the  desired  amount. 

The  character  of  the  water-bearing  material  is  of  the  greatest 
importance  in  determining  the  yield  of  the  well.  In  quicksand, 
water  is  usually  present  in  ample  quantities,  yet  owing  to  the 
extremely  fine  particles  of  which  the  quicksand  is  composed, 
its  presence  as  a  water-bearing  soil  is  highly  undesirable. 

Flowing  Wells. — Mowing  wells  are  obtained  in  places  where 
water  is  confined  in  the  earth,  under  sufficient  pressure  to  lift 
it  to  the  surface,  through  an  opening  made  to  the  water-bearing 
stratum.  These  are  known  as  artesian  wells,  from  the  fact  that 
they  were  first  used  in  Artois  (anciently  called  Artesium)  in 
France.  In  order  that  water  may  have  sufficient  head  to  lift 
it  to  the  surface,  it  must  be  confined  under  impervious  clay  or 
other  bed  of  earth,  and  with  its  source  at  a  level  considerably 
higher  than  its  point  of  exit.  The  source  of  supply  for  flowing 
wells  is  often  at  a  great  distance.  Because  of  the  fact  that 
flowing  wells  are  shut  off  from  the  surface  by  an  impervious 
layer  of  earth,  the  possibility  of  pollution  from  the  surface  is 
effectively  prevented.  Any  contamination  of  the  water  must 
come  from  a  distance  and  enter  the  water  at  its  source.  As 
pollution  rarely  extends  through  the  ground  to  any  great  lateral 
distance,  artesian  waters  are  seldom  polluted.  The  water  from 
artesian  wells  often  is  heavy  with  mineral  matter  and  in  many 
cases  is  unfit  for  drinking  on  that  account. 

CONSTRUCTION  OF  WELLS 

Wells  are  constructed  by  different  methods,  depending  on  the 
character  of  the  soil  in  which  they  are  sunk.     Their  excavation 


WATER  SUPPLY  139 

is  usually  accomplished  by  one  of  three  general  methods:  by 
digging;  by  driving  a  pipe  into  the  earth  until  it  penetrates  the 
water-bearing  stratum;  or  by  boring  a  hole  with  an  enlarged 
earth  auger,  into  the  water-bearing  soil.  Artesian  wells  are 
made  by  drilling  with  a  device  suitable  for  making  a  small  and 
very  deep  hole. 

Dug  Wells. — In  shallow  wells  the  water  seeps  through  the  soil 
from  local  precipitation.  Deep  wells  are  those  from  which  the 
water  is  brought  to  the  surface  through  an  impervious  geologic 
formation,  as  a  bed  of  clay  or  rock,  and  from  a  depth  greater 
than  that  from  which  water  may  be  lifted  by  atmospheric  pres- 
sure. The  fact  that  a  deep  well  originates  from  a  source  that 
entirely  differs  from  that  of  the  shallow  well  accounts  for  the 
difference  in  chemical  composition  which  frequently  exists  in  the 
water  from  the  two  types  of  wells  in  the  same  neighborhood. 

The  form  of  the  dug  well  is  generally  that  of  a  cylindrical 
shaft  4  feet  or  more  in  diameter  and  of  depth  depending  on  the 
location  of  the  water-bearing  stratum.  Where  the  character  of 
the  soil  is  such  that  the  seepage  is  slow  and  the  water  does  not 
flow  into  the  well  as  fast  as  the  pump  will  remove  it,  the  well  must 
contain  a  considerable  volume  to  supply  the  period  of  greatest 
demand.  Wells  of  this  kind  are  commonly  walled  with  brick  or 
stone  to  keep  the  sides  in  place  and  to  prevent  the  entrance  of 
surface  waters.  The  top  of  this  curb  should  be  brought  above  the  / 
surface  of  the  ground  and  should  be  made  water-tight  to  prevent  Y 
the  entrance  of  surface  waters.  The  space  around  the  curb, 
at  the  surface,  should  be  graded  to  drain  the  water  away  from  the 
well.  There  should  be  no  chance  for  the  water  to  collect  in 
pools  about  the  well;  it  should  be  conducted  away  in  a  gutter 
to  the  place  of  final  disposal.  The  well  should  be  covered  with  a 
platform  of  concrete  or  planking  which  will  allow  no  water  to 
enter  from  the  surface. 

Wells  of  this  order  are  sometimes  dug  to  great  depth  before 
the  water-bearing  stratum  is  encountered;  this  may  sometimes 
be  reached  only  after  a  great  amount  of  expense  and  labor.  The 
historic  Joseph  Well,  near  Cairo,  Egypt,  is  an  open  shaft,  18  by 
24  feet  in  area,  sunk  through  solid  rock  160  feet. 

Open  Wells. — Open  wells  have  long  been  condemned  as  insani-  « 
tary.     The  familiar  open  well  of  the  "Old  Oaken  Bucket"  type 


140 


MECHANICS  OF  THE  HOUSEHOLD 


is  an  inviting  receptacle  for  the  deposit  of  all  manner  of  refuse, 
which  once  inside  remains  until  it  is  disintegrated.  These  wells 
become  the  final  resting  place  of  many  small  animals  and  all 
manner  of  creeping  things,  in  search  of  water.  The  open  top 
receives  wind-blown  matter  in  the  form  of  leaves  and  dust,  much 
of  which  is  in  the  nature  of  polluting  material. 

The  Ideal  Well. — In  the  case  of  a  well  which  yields  pure  water, 
every  precaution  should  be  taken  to  prevent  its  pollution.  The 
ideal  form  of  construction  is  that  shown  in  Fig.  125.  In  this 

well,  the  curbing  C  is  of  heavy 
concrete  that  extends  above  the 
natural  surface  of  the  ground,  to 
prevent  the  entrance  of  surface 
water,  and  that  from  seepage 
through  the  upper  stratum  of  the 
soil.  The  reinforced-concrete  top 
forms  a  close  joint  with  the  curb 
to  prevent  the  entrance  of  waste 
water  and  all  .animal  life.  The 
pump  is  of  iron,  secured  to  the  well 
cover  by  bolts,  set  in  the  concrete. 
The  trough  of  concrete  G  con- 
ducts the  waste  water  from  the 
well  to  a  safe  distance.  The  earth 
FIG.  125.— ideal  form  of  well  curb-  about  the  well  is  so  graded  as  to 

ing  with  cover  and  drain  made  of  permit  no  water  to  stand  in 
concrete. 

pools. 

Coverings  of  Concrete. — The  use  of  concrete  for  the  coverings 
of  wells,  cisterns  and  springs  has  become  a  recognized  form  of 
the  best  construction.  It  is  not  more  expensive  than  other  good 
materials  and  when  properly  executed  it  forms  an  imperishable 
protection  and  gives  a  neat  appearance.  The  spring  cover  in 
Fig.  126,  and  the  cistern  top  in  Fig.  127  are  illustrations  of 
its  application. 

Artesian  Wells. — Artesian  wells  are  made  by  boring  into 
the  earth  until  the  drill  reaches  the  artesian  stratum,  the  in- 
ternal pressure  forces  the  water  through  the  opening  to  the 
surface.  They  are  usually  small  in  diameter  and  often  of 
great  depth.  In  some  areas  the  artesian  flow  is  found  a  few 


WATER  SUPPLY 


141 


feet  below  the  surface,  but  generally  it  is  much  deeper  and  3000 
feet  is  not  an  unusual  depth. 

The  pressure  and  amount  of  flow  from  these  wells  is  sometimes 
sufficient  to  permit  the  water  being  used  for  the  generation  of 
power.  Small  waterwheels  are  not  uncommonly  driven  in  this 
way  and  the  power  used  for  the  generation  of  electricity  for 
lighting  and  running  small  household  appliances. 

Driven  Wells. — In  localities  where  the  nature  of  the  soil 
gives  opportunity,  wells  are  made  by  driving  a  pipe  to  the  re- 
quired depth.  Wells  of  this  character  are  usually  made  in  places 
where  the  water-bearing  soil  is  of  sand  or  gravel.  The  pipe 


FIG.  126. — Concrete  cover  for 
a  spring. 


FIG.  127. — Concrete  cistern  top. 


terminates  in  a  sand-point  such  as  that  of  Fig.  128.  This  sand- 
point  is  a  perforated  pipe  with  a  pointed  end,  that  facilitates 
driving.  The  perforations,  as  shown  in  the  point  P,  form  a 
strainer  which  allows  the  water  to  enter  the  pipe  but  prevents 
the  sand  from  filling  the  opening. 

In  the  use  of  driven  wells,  the  water-bearing  soil  must  be 
sufficiently  open  to  allow  the  water  to  flow  into  the  pipe  as  fast 
as  the  pump  takes  it  away. 

Bored  Wells. — In  many  localities  the  water-bearing  stratum 
is  of  such  nature  as  to  give  a  ready  flow  of  water  but  yet  not 
sufficient  to  permit  of  the  use  of  a  sand-strainer;  if,  however,  the 
opening  is  somewhat  enlarged,  the  water  will  enter  with  sufficient 
rapidity  to  supply  a  pump.  In  such  cases  bored  wells  are  quite 
generally  used.  They  are  made  by  boring  a  hole  of  the  required 
size  with  an  earth  auger.  These  wells  are  made  of  any  size  up 
to  2  feet  in  diameter.  They  are  often  called  tubular  wells  because 


142 


MECHANICS  OF  THE  HOUSEHOLD 


they  are  lined  with  iron  tubing  or  tile,  to  prevent  the  earth  from 
refilling  the  hole. 

Cleaning  of  Wells. — Very  few  dug  wells  are  so  constructed  as 
to  exclude  dust  and  washings  from  the  ground.     It  is,  therefore, 


FIG.   128. — Driven  well  with  a  sand-point  strainer. 

necessary  that  they  be  occasionally  cleaned.  Accumulations 
from  these  causes  may  be  sufficient  to  hinder  the  entrance  of  the 
water  to  the  well  and  thus  lessen  its  capacity. 

Gases  in  Wells. — One  of  the  commonest  gases  found  in  wells  is 
carbon  dioxide  (carbonic  acid  gas).  It  may  be  detected  by 
lowering  a  lighted  candle  or  lantern  to  the  bottom.  If  the  gas 


WATER  SUPPLY  143 

is  present  in  dangerous  quantity,  the  flame  will  be  extinguished. 
Death  from  asphyxiation  due  to  this  gas  is  not  an  uncommon 
occurrence,  to  persons  descending  into  wells.  Before  entering  a 
well,  the  test  described  above  should  be  applied,  as  a  precaution 
against  accident.  Carbon  dioxide  is  a  colorless,  odorless  gas 
in  which  a  person  will  drown  as  readily  as  in  water. 

Peculiarities  of  Wells.  —Owing  to  the  formation  of  the  water- 
bearing earths,  from  which  they  receive  their  water,  many  wells 
possess  marked  peculiarities  of  behavior  that  often  give  rise  to 
local  reputation  because  of  their  vagaries.  These  characteristics 
have  been  classified  into  breathing  wells,  blowing  wells,  sucking 
wells,  etc.  These  effects  are  in  almost  every  case  due  to  variation 
of  barometric  pressure.  The  ordinary  level  of  the  water  in  a 
well  is  governed  by  the  variation  of  rainfall,  melting  of  snow  or 
the  release  of  water  by  the  thawing  of  frozen  ground.  It  often 
occurs,  however,  that  the  head  of  water  is  markedly  influenced 
by  storms,  when  a  rise  of  the  level  of  the  water  occurs  at  the 
time  of  low  barometric  pressure  during  the  storm  period.  This 
effect  is  often  noticed  in  flowing  wells.  Many  wells,  at  the  ap- 
proach of  storms,  yield  roily  water  to  such  an  extent  that  where 
the  water  is  normally  clear  it  may  become  for  a  period  entirely 
unfit  to  drink,  because  of  the  matter  held  in  suspension.  All 
of  these  effects  are  accounted  for  by  the  varying  atmospheric 
pressure.  At  the  time  of  high  barometer,  a  well  that  ordinarily 
flows  freely  will  have  to  be  pumped,  the  additional  pressure  of 
the  air  holding  back  the  water  to  an  extent  representing  several 
feet  of  head.  The  change  of  an  inch  in  the  barometric  pressure 
will  produce  slightly  more  than  a  foot  in  head  of  water.  At  the 
time  of  storms,  the  barometer  is  sometimes  abnormally  low  which 
will  produce  a  corresponding  rise  of  water  in  the  well.  At  such 
time  the  free  flow  of  water  into  a  dug  well,  from  the  usual  source 
of  supply,  will  cause  such  a  rapid  flow  of  water  through  the 
passages  in  the  earth  as  to  carry  with  the  water  the  sediment 
that  produces  roily  water  in  the  well.  This  sediment  will  settle 
after  a  while  and  the  water  will  again  be  clear. 

Breathing  Well. — •  Wells  of  this  kind  are  most  common  in  areas 
where  the  water-bearing  earth  is  of  rock  formation;  particularly 
in  limestone  areas,  where  caves  and  cavities  are  common.  It 
sometimes  happens  that  in  the  neighborhood  of  a  well  there  is  a 


144  MECHANICS  OF  THE  HOUSEHOLD 

cavity  in  the  earth  of  considerable  volume,  the  only  entrance  to 
which  is  through  the  well  and  that  being  under  usual  conditions 
covered  by  water,  a  foot  or  more  in  depth.  With  such  a  forma- 
tion the  conditions  are  right  for  a  breathing  well.  At  times  of 
high  barometer  the  water  is  depressed  and  the  air  will  flow  into 
the  cavity  through  the  well,  when  the  well  is  said  to  inhale. 
This  inward  flow  of  air  will  continue  until  the  air  pressure  in  the 
cavity  is  equal  to  that  of  the  outer  air;  and  if  the  cavity  is  large 
and  the  opening  small,  the  inward  flow  of  air  may  continue  for 
hours,  even  for  days.  With  a  fall  of  barometric  pressure,  the 
air  in  the  cavity,  being  at  a  higher  pressure  than  the  external 
air,  the  air  will  flow  outward  and  the  well  is  said  to  exhale. 

Freezing  Wells. — In  cold  climates,  particularly  in  territory 
possessing  cavernous  limestone  deposits,  breathing  wells  often 
freeze  in  winter.  When  large  volumes  of  frigid  air  are  drawn  into 
a  well,  the  amount  of  heat  taken  from  the  water  is  sufficient  to 
freeze  it,  and  stop  the  supply  of  water.  •  This  effect  is  some- 
times remedied  by  plugging  the  well  at  the  top,  so  that  the  influx 
of  cold  air  is  prevented  and  the  water  does  not  freeze. 


PUMPS 

Pumps  for  lifting  and  elevating  water  are  made  of  both  wood 
and  iron  in  almost  endless  variety;  but  for  domestic  purposes 
they  are  of  two  general  types — the  lift  pump  and  the  force  pump 
— which  include  features  that  are  common  to  all.  The  lift  pump 
is  intended  for  use  in  lifting  water  from  low-head  cisterns  and 
wells,  the  depth  of  which  is  not  beyond  the  head  furnished  by 
atmospheric  pressure.  The  force  pump  performs  the  work  of  a 
lift  pump  and  in  addition  forces  the  water  from  the  outlet  at  a 
pressure  to  suit  any  domestic  application.  These  pumps  are 
made  by  manufacturers  in  a  great  variety  of  forms,  but  the  essen- 
tial parts  are  the  same  in  all  pumps  intended  for  a  single  purpose. 
The  principle  of  operation  is  the  same  in  all  pumps  of  any  type. 
The  difference  in  mechanism  of  pumps  intended  for  the  same 
purpose  is  only  in  the  form  and  arrangement  of  the  parts. 

The  Lift  Pump. — The  kitchen  pump  is  an  example  of  the  lift 
pump.  It  is  universally  used  for  household  purposes  where  water 
is  to  be  raised  from  cisterns,  etc.,  and  is  most  commonly  made 


WATER  SUPPLY 


145 


" priming"  would  raise  water  15  feet  with  consider- 


throughout  of  cast  iron.  Fig.  129  illustrates  one  form,  sometimes 
called  the  pitcher  pump,  because  of  the  slight  resemblance  to  the 
article.  It  frequently  carries  the  name  cistern  pump  from  the 
fact  that  it  very  generally  is.. used  to  lift  water  from  cisterns. 

Although  water  may  be  raised  34  feet  with  a  theoretically 
perfect  pump  and  with  a  barometric  pressure  of  30  inches  the 
actual  limit  is  much  lower.  In  use,  20  feet  is  probably  about  the 
limit  and  10  feet  or  less  is  that  of  common  practice.  A  pump 
that  requires 

able  difficulty  for  reasons  that  will  ap- 
pear later.  In  Fig.  129  is  shown  a  sec- 
tional view  of  the  working  parts  of  the 
kitchen  pump,  the  action  and  general 
form  of  which  apply  to  any  lift  pump. 
The  body  of  the  pump  contains  a  cylin- 
der,  in  which  closely  fits  a  piston  P,  con- 
taining a  valve  A.  At  the  bottom  of 
the  cylinder  is  an  additional  valve  B. 
The  piston  and  two  valves  constitute 
the  working  parts  of  the  pump.  The 
water  is  lifted  through  the  pipe  S,  and  is 
discharged  at  D. 

The  action  of  the  pump  is  as  follows: 
With  the  piston  at  the  bottom  of  the 
cylinders  and  with  no  water  in  the  pump, 
the  handle  is  forced  down,  which  action 
raised  the  piston.  In  so  doing  the  air 
below  it  is  rarefied.  The  reduction  of 
pressure  due  to  the  rarefication  of  the 
air  allows  the  water  to  rise  in  the  pipe  S  correspondingly.  After 
repeated  strokes  of  the  piston,  the  water  reaches  the  valve  B, 
which  raises  to  let  it  pass,  but  immediately  closes  at  the  end 
of  the  upward  stroke.  When  the  space  between  the  piston 
and  the  valve  B  is  filled  with  water,  each  descent  of  the  piston 
forces  the  water  through  the  valve  A ;  and  when  the  .piston  is 
raised,  the  water  is  lifted  out  through  the  spout. 

The  valve  A  is  a  loose  piece  of  cast  iron,  surfaced  on  the  lower 
side  to  make  good  contact  with  the  piston.     The  valve  B  is  of 
cast  iron  fastened  to  a  piece  of  leather  by  a  screw.     The  leather 
10 


FIG.  129.  — Sectional 
drawing  of  the  kitchen  pump 
showing  its  working  parts. 


146 


MECHANICS  OF  THE  HOUSEHOLD 


makes  a  joint  with  the  valve-seat  and  furnishes  an  excellent 
valve  for  its  use.  In  order  to  keep  the  plunger  P  tight  in  the 
cylinder,  it  is  surrounded  with  a  leather  gasket.  Should  this 
gasket  become  worn,  as  it  will  in  time,  the  plunger  fits  loosely  in 
the  cylinder  and  the  pump  will  lift  the  water  with  difficulty, 
because  of  the  leakage  around  the  gasket.  Should  the  valve  B 
leak,  the  water  will  gradually  run  back  into  the  pipe  S,  and  the 
pump  when  left  idle  will  lose  its  " priming."  The  plunger  and 
the  valve  B  are  the  parts  most  likely  to  get  out  of  order.  If  the 
gasket  around  the  piston  P  is  very  much  worn,  and  there  is  no 


H 


FIG.   130. — Method  of  attaching  the  house 
pump  to  kitchen  sink. 


FIG.  131. — Sectional  drawing 
of  the  force  pump  showing  its 
working  parts. 


water  in  cylinder,  the  pump  will  require  priming  before  the  water 
can  be  raised.  If  the  pump  contains  no  water  and  is  left  standing 
for  a  considerable  time,  the  leather  parts  of  the  valve  dry  out  and 
shrink;  when  the  pump  is  again  put  into  use,  the  valves  will  fail 
to  work  properly,  until  the  leathers  are  again  water-soaked. 
Water  is  poured  into  the  top  of  the  pump  until  the  cylinder  is 
filled,  and  as  soon  as  the  leather  becomes  water-soaked  and  fills 
the  cylinder,  the  piston  will  again  perform  its  function. 

The  Force  Pump. — The  house  force  pump  is  often  used  in  place 
of  the  ordinary  lift  pump,  when  no  other  means  is  at  hand  for 
providing  water  under  pressure.  It  furnishes  a  limited  means 


WATER  SUPPLY 


147 


for  lawn  sprinkling  and  gives  some  degree  of  fire  protection  in 
isolated  places.  It  may  be  made  a  part  of  the  kitchen  sink  as 
shown  in  Fig.  130,  by  use  of  the  attachment  that  appears  in 
detail  under  the  sink.  This  type  of  pump  may  be  used  in  small 
water-supply  plants,  such  as  that  of  Fig.  143;  or  in  connection 
with  small  pressure  tanks  for  the  same  purpose.  It  differs 
somewhat  in  construction  from  the  lift  pump,  in  that  it  has  no 
valve  in  the  piston  and  is  provided  with  a  check  valve  and  an 
air  chamber  for  generating  pressure  to  the  discharged  water. 

Fig.  131  shows  the  essential  parts  of  the  force  pump  and 
furnishes  a  means  of  describing  its  operation.  All  force  pumps 
possess  the  same  parts  and  the  operation 
described  applies  with  equal  force  to  all.  A 
valve  A  is  located  in  the  bottom  of  the 
cylinder  and  the  check  valve  B  prevents  the 
return  of  the  water  to  the  cylinder  after  it 
has  been  forced  out  of  the  pump.  The  ac- 
tion of  the  pump  in  raising  the  water  is  the 
same  as  in  the  lift  pump  but  when  the  water 
fills  the  cylinder  and  the  piston  descends, 
the  water  is  forced  through  the  valve  B  and 
out  at  D.  If  the  outlet  pipe  is  slightly 
smaller  than  the  opening  in  the  valve  B,  some 
of  the  water  will  enter  the  air  chamber  C 
and  compress  the  air.  The  pressure  thus 
generated  will  immediately  tend  to  force 
the  water  out  and  in  course  of  ordinary 
pumping  will  send  out  a  steady  stream  in-  FIG.  132.  —  Tank 
stead  of  the  intermittent  flow  of  the  lift  pump  commonly  used 

in  small  domestic  water 

pump.     Without  the  air  chamber,  the  flow  supply  plants. 
from  this  pump  will  be  a  series  of    pulsa- 
tions that  attain  maximum  force  with  each  descent  of  the  piston. 
Tank  Pump.— The  type  of  pump  used  with  a  water-supply 
plant  will  depend  entirely  on  the  amount  of  water  that  is  used. 
If  the  supply  of  water  to  be  provided  is  for  only  one  or  two 
people  the  house  force  pump  such  as  that  of  Fig.  130  will  suffice; 
but  when  a  greater  number  of  people  are  to  be  supplied,  a  force 
pump   of   the  type  shown  in  Fig.  132  is  quite  generally  used. 
These  pumps  are  made  in  a  variety  of  patterns  and  are  commonly 


148  MECHANICS  OF  THE  HOUSEHOLD 

termed  tank  pumps.  The  one  shown  in  the  Fig.  132  is  a  double- 
acting  force  pump  in  that  the  cylinder  receives  and  discharges 
water  at  each  stroke  of  the  piston.  The  air  chamber  is  located 
at  A.  Directly  beneath  the  air  chamber  is  the  valve  chest  in 
which  are  located  the  valves  which  regulate  the  entrance  and 
discharge  of  the  water.  As  used  in  the  average  domestic  plant 
the  cylinders  are  3  or  4  inches  in  diameter. 

WELL  PUMPS 

The  pumps  intended  for  raising  water  from  wells  are  practically 
the  same  in  construction  as  the  house  pump,  except  that  they  are 
intended  to  deliver  a  greater  volume  of  water  and  sometimes  to 
work  under  a  different  condition,  as  that  of  the  deep  well  pump. 
Well  pumps  have,  therefore,  assumed  certain  standard  forms  that 
differ  only  in  the  styles  of  mechanism  employed  by  different 
manufacturers. 

The  one  shown  in  Fig.  133  furnishes  a  good  example  of  a 
general-purpose  iron  pump  which  may  be  used  either  as  a  force 
pump  or  a  lift  pump.  It  represents  also  the  general  construction 
of  a  deep-well  pump,  where  the  water  must  be  lifted  from  a  level, 
below  that  at  which  a  lift  pump  will  work. 

The  piston  and  valves  are  enclosed  in  the  cylinder  C,  placed 
below  the  surface  of  the  water  in  the  well.  This  cylinder  also 
appears  in  section  in  the  small  drawing,  showing  the  details  of  the 
valve.  The  operation  of  this  pump  is  identical  to  that  'of  the 
lift  pump  already  described,  but  the  addition  of  an  air  chamber 
gives  it  the  necessary  facility  to  produce  a  continuous  flow  of 
water.  In  order  to  prevent  the  air  in  the  air  chamber  from 
escaping,  the  pump  rod  is  surrounded  with  the  necessary  stuffing- 
box  which  is  usually  packed  with  candle  wicking  to. assure  a  good 
joint.  In  deep  wells  the  tube  is  elongated  sufficiently  to  place 
the  cylinder  C  below  the  surface  of  the  water  in  the  well.  Such 
pumps  are  operated  either  by  hand  or  by  power. 

Wooden  Pump.— The  wooden  pump  of  Fig.  134  furnishes  a 
good  illustration  of  a  type  that  was  formerly  used  in  great 
numbers.  It  is  an  inexpensive  and  efficient  pump  made  almost 
entirely  of  wood  except  the  cylinder  which  is  quite  generally 
made  of  iron,  lined  with  enamel.  The  valve  and  the  piston 


WATER  SUPPLY 


149 


with  its  valves  are  made  of  wood,  but  faced  with  leather  to  insure 
tight  joints.  The  piston  is  also  provided  with  leather  packing 
to  make  it  tight  in  the  cylinder.  The  action  of  the  pump  is  the 


FIG.  133. — Sectional  view  of  a  well 
with  an  iron  cylinder  pump,  placed  for 
deep-well  pumping. 


FIG.  134. — Sectional  view  of  a 
well  and  wooden  pump  for  shallow 
pumping. 


same  as  that  already  described.  The  wooden  tube  is  made  in 
sections  joined  together  by  taper  joints  that  are  driven  into  place. 
The  piece  at  the  side  of  the  pump  is  provided  to  drain  the  water 
from  above  the  piston,  as  a  precaution  against  freezing  during 
extremely  cold  weather.  The  rod,  when  raised,  opens  an  orifice 


150  MECHANICS  OF  THE  HOUSEHOLD 

that  leads  to  the  inside  of  the  pump  and  permits  the  water  to 
drain  into  the  well. 

Pumps  for  Driven  Wells. — The  method  of  constructing  driven 
wells — that  of  driving  a  pipe  into  the  earth  to  the  water-bearing 
stratum  of  sand  or  gravel — requires  a  special  end  to  prevent  the 
pump  tube  from  becoming  stopped.  In  order  that  the  fine 
material  may  not  enter  and  fill  the  lower  end  of  the  tube,  a 
sand-point  is  used,  such  as  that  shown  in  Fig.  128.  It  is  made  of 
perforated  brass  tubing  and  provided  with  a  sharpened  end  to 
facilitate  driving.  The  perforations  act  as  a  strainer  that  keeps 
out  all  but  the  fine  particles  which  will  pass  the  pump  valves. 
Sand-points  are  made  with  strainers  of  various  degrees  of  fineness 
to  suit  the  different  conditions  of  soils.  These  strainers  may 
in  the  course  of  time  become  filled  with  particles  of  the  soil  that 
lodge  in  the  perforations  and  the  outside  become  so  encrusted  as 
to  prevent  the  entrance  of  the  water.  In  such  case,  the  pipe 
must  be  pulled  out  of  the  ground  and  the  point  replaced  by  a  new 
one.  In  Fig.  128  is  shown  a  driven  well  with  the  sand-point  in 
the  water-bearing  stratum.  If  the  small  particles  of  earth  clog 
the  strainer  the  pump  will  "work  hard"  and  yield  only  a  portion 
of  the  water  the  soil  is  capable  of  giving  when  the  strainer  is 
clear. 

Deep-well  Pumps. — The  principle  of  operation  as  described 
in  the  lift  pump  takes  advantage  of  the  atmospheric  pressure  to 
lift  the  water  above  the  first  valve.  The  limiting  distance  to 
which  water  can  be  lifted  by  the  atmospheric  pressure  will  depend 
on  the  altitude  and  the  atmospheric  pressure.  With  the  normal 
atmospheric  pressure  at  sea  level,  water  can  be  lifted,  theoretic- 
ally, 34  feet,  but  in  practice  the  limiting  value  is  never  even 
approximated.  The  pump  is  usually  placed  within  10  or  12  feet 
of  the  water  and  20  feet  is  about  the  limit  of  distance.  The 
reason  for  this  is  because  of  the  impossibility  of  keeping  the  joints 
tight  in  the  valve  and  tubing. 

Where  water  is  to  be  raised  from  a  deep  well,  the  cylinder  with 
its  piston  is  placed  near  the  water  and  the  tube  and  rod,  as  that 
of  Fig.  133,  connects  the  cylinder  with  the  pump  stock.  After 
the  water  has  passed  the  valve  in  the  piston,  it  may  be  readily 
lifted  to  the  pump  stock.  In  this  way  water  is  raised  from  wells 
of  great  depth. 


WATER  SUPPLY 


151 


Tubular  -well  Cylinders.  —  Tubular  wells  that  are  cased  with 
iron  pipe  are  provided  with  a  special  type  of  pump 
cylinder  that  admits  of  deep-well  operation.  The 
casing  of  the  well  being  in  place,  the  cylinder  shown 
in  Fig.  135  is  forced  down  the  casing  to  its  proper 
place,  the  spring  S  holding  it  in  place  until  it  is  firmly 
secured.  A  special  seating  tool  is  now  lowered  into 
the  casing  and  attaches  at  T  to  the  coupling;  as  the 
tool  is  turned,  rubber  packing  R  is  expanded,  locking 
the  cylinder  firmly  to  the  casing.  This  makes  a  com- 
plete pump  cylinder,  which  with  the  piston  P  in  place 
is  operated  as  any  other  pump. 

Chain  Pumps.  —  In  shallow  wells  and  other  sources 
of  supply,  where  water  is  to  be  lifted  only  a  short 
distance,  chain  pumps  have  been  used  to  a  great  ex- 
tent, because  of  their  quick  action.  This  pump,  as 
shown  in  Fig.  136,  elevates  the  water  by  an  endless 
chain  being  drawn  through  the  tube,  the  lower  end 
of  which  is  below  the  surface  of  the  water.  The  chain 
is  provided  at  intervals  with  discs  or  rubber  or  iron, 
that  fit  the  bore  of  the  tube  and  form  pistons  which 
elevate  the  water  as  they  ascend.  The  chain  passes 
around  a  wheel  in  the  upper  part  of  the  box  and  is 

worked  by  the  crank.  Chain  pumps  are  not 
usually  employed  to  elevate  water  a  greater 
height  than  20  feet.  They  are  not  efficient 
pumps  and  are  not  sanitary  because  of  the 
opportunity  they  give  for  admitting  pollut- 
ing material  to  the  well.  Their  one  advant- 
age is  that  of  quick  action  in  elevating  water 
short  distances. 

RAIN-WATER  CISTERNS 
Cisterns  for  the  storage  of  rain  water  have 
been  used  from  the  time  immemorial  and  are 
FIG.  136.—  Chain    constructed  in  a  great  variety  of  forms.     For 
pump  often  used  in    household  use  they  are  often  made  in  the  form 
of  wooden  or  metal  tanks,  either  elevated  or 
placed  in  the  basement;  the  greater  number,  however,  are  of 
the  underground  variety  made  of  brick  or  concrete. 


152  MECHANICS  OF  THE  HOUSEHOLD 

Wooden  cisterns  are  made  by  manufacturers  in  different  sizes 
and  shipped  to  the  user  " knocked  down; "  that  is,  they  are  taken 
apart  and  the  staves,  bottom  and  hoops  are  shipped,  packed  in 
small  space  to  save  space  in  transportation.  Under  some  condi- 
tions they  give  good  service  but  are  apt  to  leak  at  times  and 
require  attention  on  that  account.  In  damp  basements  they 
give  out  the  disagreeable  odor  of  damp  wood. 

Tanks  made  of  galvanized  iron  are  much  used  as  cisterns  for 
temporary  use.  They  are  inexpensive  and  give  good  service 
but  are  short-lived.  Possibility  of  leakage  is  their  greatest  dis- 
advantage. Underground  cisterns  are  built  either  in  the  base- 
ment or  outside  the  house.  They  are  quite  generally  made  jug- 
shaped,  but  are  often  constructed  of  concrete  in  square  and 
rectangular  form.  When  built  of  brick  the  walls  are  often  made 
of  a  single  course,  but  walls  made  of  two  courses  of  brick  are 
considered  better  practice.  The  walls  and  floor  are  made  water- 
tight by  plastering  with  an  inch  or  more  of  cement  mortar. 

When  cisterns  are  made  of  concrete,  the  floor  should  be  put 
in  6  inches  in  depth  and  as  soon  after  as  possible  the  walls  are  put 
up.  In  good  construction  the  walls  are  8  inches  in  thickness  of 
concrete,  made  of  1  part  good  Portland  cement,  2  parts  clean 
sand  and  4  parts  crushed  stone.  If  the  cistern  is  square  or 
rectangular  in  form  the  walls  should  be  reinforced  with  woven 
wire  or  steel  rods,  to  prevent  cracking. 

The  curb  of  the  cistern  should  extend  above  the  surface  of  the 
ground  sufficiently  to  prevent  surface  water  from  entering,  and 
the  top  should  be  covered  with  a  wood-lined  sheet-metal  cover 
to  prevent  freezing. 

Filters. — Unfiltered  cistern  water  is  not,  as  a  rule,  fit  for  drink- 
ing purposes  because  of  pollution  from  dust  and  impurities 
washed  from  the  roof,  but  for  bathing  and  laundry  work  filtered 
rain  water  is  greatly  to  be  desired. 

As  rain  water  comes  from  the  roofs  of  buildings,  there  is 
washed  into  the  cistern  a  considerable  quantity  of  dust,  leaves, 
bird  droppings  and  other  polluting  materials  which  contaminate 
and  discolor  the  water.  This  foreign  matter  is  not  injurious 
for  the  purposes  intended,  but  to  render  the  water  clear  it  should 
be  filtered  before  using. 

Filters  for  cisterns  are  quite  generally  made  of  soft  brick  laid  in 


WATER  SUPPLY 


153 


cement  mortar,  the  face  of  the  brick  being  left  uncovered.  Fig. 
137  illustrates  a  simple  and  efficient  form  of  filter  made  of  a 
single  course  of  brick.  A  space  one-fourth  to  one-third  of  the 
volume  of  the  cistern  is  left  for  the  filtered  water.  The  opening 
at  the  top  of  the  wall  must  be  large  enough  to  admit  a  man,  for 
some  sediment  will  collect  even  in  the  filtered  water  and  the  filter 
must  be  occasionally  cleaned. 


Capacity-385  Cu.  Ft. 
or  90  Barrels  of  31^ 
Gallons  each 


^  Capacity-400  Cu.  Ft. 
or  90  Barrels  of 
Gallons  each 


Down  Spout 


FIG.  137.— Cross-section  of  a  brick  curbed 
cistern  with  a  brick  filter  wall. 


FIG.   138. — Cross-section   of   a    con- 
crete cistern  with  a  brick  dome  filter. 


The  filter  shown  in  Fig.  138  is  dome-shaped  and  built  of  brick. 
The  water  is  pumped  from  inside  the  filter  and  the  suction  of 
pumping  filters  the  water  as  it  is  used.  In  this  case  the  filtering 
action  is  accelerated  by  reason  of  the  reduced  pressure  inside  the 
filter  as  the  water  is  pumped.  The  chief  disadvantage  in  this 
form  of  filter  is  the  small  area  exposed  for  the  filtering  action  and 
the  relatively  greater  amount  of  work  required  for  pumping  the 
water,  due  to  the  partial  vacuum  formed  as  the  water  is  pumped. 

The  cistern  in  Fig.  139  is  provided  with  a  catch  basin  which 
acts  as  a  strainer  for  removing  leaves,  etc.,  that  would  stain  the 
water.  It  is  made  in  the  form  of  a  concrete  basin  and  partly 
filled  with  gravel.  The  filter  in  this  case  is  formed  by  a  depres- 
sion in  the  cistern  floor.  A  section  of  tile  is  placed  on  the  floor, 


154 


MECHANICS  OF  THE  HOUSEHOLD 


and  around  it  is  filled  the  filtering  material  of  gravel  and  sand. 
Filters  of  this  kind  are  often  filled  with  charcoal  or  other  materials 
that  are  expected  to  purify  the,  water.  They  are  usually  in- 
efficient because  their  value  as  absorbers  of  polluting  agents  is 
short-lived  and  unless  the  materials  are  frequently  renewed  they 
are  valueless  and  sometimes  a  detriment  to  rapid  filtration. 


FIG.  139. — Cross-section  of  a  concrete  cistern,  containing  a  sand  filter. 


THE  HYDRAULIC  RAM 

In  places  where  its  use  is  possible,  the  hydraulic  ram  is  a  most 
convenient  and  inexpensive  means  of  mechanical  water  supply. 
It  is  simple  in  construction,  requires  very  little  attention  and 
its  cost  of  operation  is  only  the  labor  necessary  to  keep  it  in 
repair.  Whenever  a  sufficient  supply  of  water  will  admit  of  a 
fall  of  a  few  feet,  the  hydraulic  ram  may  be  used  as  a  pump  for 
forcing  the  water  to  a  distant  elevated  point,  where  it  may  be 
utilized  for  all  domestic  purposes.  The  water  may  be  used 
directly  from  the  ram  or  stored  in  an  elevated  tank  as  a  reserve 
supply;  or  accumulated  in  a  pressure  tank,  where  additional 
pressure  is  required. 

The  hydraulic  ram  has  been  used  since  1796,  when  it  was 
invented  by  Joseph  de  Montgolfier.  The  principle  of  its  opera- 


WATER  SUPPLY  155 

tion  is  that  of  the  utilization  of  the  energy  of  flowing  water.  The 
running  water  is  made  to  give  up  a  portion  of  its  momentum  to 
elevate  a  part  of  the  water,  and  transport  it  to  a  considerable 
distance.  If  the  source  of  supply  and  the  fall  is  sufficient,  almost 
any  amount  may  be  elevated  and  carried  to  a  great  distance. 
Large  rams  are  sometimes  used  as  a  means  of  water  supply  for 
small  towns.  In  the  use  of  the  double-acting  ram,  one  source 
of  water  may  be  used  to  operate  the  ram  and  water  from  an 
entirely  different  source  may  be  delivered.  It  sometimes 
happens  that  a  muddy  stream  and  a  clear  spring  are  so  located, 
that  the  water  of  the  stream  can  be  utilized  to  furnish  the  energy 
for  conveying  the  spring  water  to  a  point  where  it  is  desired  for 
use.  This  is  accomplished  by  the  double-acting  ram  in  a  most 
efficient  manner. 

Single-acting  Hydraulic  Ram. — Fig.  140  represents  the  instal- 
lation of  a  single-acting  hydraulic  ram,  placed  to  take  water  from 


FIG.  140. — Hydraulic  ram  driven  by  the  water  from  a  spring. 

a  spring  E,  and  deliver  it  to  an  elevated  tank  at  the  house  on  the 
hill. 

In  case  the  ram  must  be  located  at  a  considerable  distance 
from  the  spring  in  order  to  attain  the  required  fall,  a  standpipe 
D — slightly  larger  than  the  supply  pipe — is  used  to  take  ad- 
vantage of  the  full  force  of  the  water.  In  long  pipes,  the  friction 
of  the  flowing  water  absorbs  a  considerable  amount  of  the  energy 
of  flow  and  a  standpipe,  located  as  indicated  at  D,  in  the  picture, 
will  assure  the  full  force  of  the  flowing  water  in  the  ram. 

The  ram  is  commonly  placed  in  an  underground  pit  as  protec- 
tion from  freezing  during  cold  weather,  and  a  drain  from  the 
bottom  of  the  pit  conducts  the  waste  water  away.  The  supply 


156 


MECHANICS  OF  THE  HOUSEHOLD 


pipe  or  drive  pipe  B  and  delivery  pipe  C  are  buried  underground 
below  the  frost  line  as  a  protection  from  freezing. 

In  Fig.  141  a  sectional  view  of  the  ram  shows  all  of  the  working 
parts.  The  air  chamber  G  is  shown  partly  filled  with  water;  the 
impetus  valve  D  is  that  part  of  the  ram  which  checks  the  flow  of 
the  running  water  and  forces  a  part  of  it  through  the  valve  E,  at 
the  bottom  of  the  air  chamber. 

When  inactive  the  valve  D  stands  open  and  as  the  water  enters 
from  the  pipe  A,  it  flows  through  the  valve  to  the  waste  pipe  but 
as  soon  as  the  full  force  of  the  water  bears  on  the  valve  it  will 
suddenly  close.  This  sudden  stop  of  the  flowing  water  will  lift 


FIG.   141. — Cross-section  of  a  single-acting  hydraulic  ram. 

the  valve  E,  and  the  energy  of  flow,  due  to  its  sudden  stopping, 
will  force  some  of  the  water  into  the  chamber  G.  As  this  action 
occurs  the  upward  pressure  against  the  valve  D  is  released  and 
it  reopens  but  immediately  closes  again  as  the  water  begins  to 
flow.  This  process  is  kept  up,  each  closure  of  the  valve  sending 
a  little  water  into  the  air  chamber.  As  the  water  gradually  fills 
the  air  chamber,  it  is  subjected  to  the  same  action  as  was  de- 
scribed in  the  pressure  tank,  the  air  above  the  surface  being  com- 
pressed and  the  pressure  developed  in  the  space  G  forces  the  water 
out  through  the  delivery  pipe  where  it  attains  a  force  that  is  a 
factor  of  the  height  of  the  original  fall. 

The  air  in  the  chamber  G,  is  subject  to  the  same  conditions 


WATER  SUPPLY 


157 


of  loss  as  that  of  the  pressure  tank,  and  to  be  assured  of  a  supply, 
to  give  pressure  to  the  water,  some  air  must  be  carried  into  the 
chamber  with  the  water.  For  this  purpose  the  valve  F  pro- 
vided. After  the  chamber  is  partially  filled,  there  occurs  a  re- 
action in  the  flow  of  water  at  each  closure  of  the  valve,  which 
causes  a  little  air  to  be  drawn  in  through  the  valve  F  with  each 
impulse.  This  air  bubbles  up  through  the  water  and  enters 
the  chamber  where  it  assures  an  elastic  cushion  for  closing  the 
valve  E. 

The  flow  of  water  from  the  supply  pipe  is  regulated  at  H  by  a 
nut  on  the  stem  of  the  impetus  valve  which  permits  its  regulation. 
Closing  the  valve  slightly  causes  a  less  supply  of  water  to  be 
delivered;  opening  the  valve  wider  gives  a  greater  supply. 


FIG.   142. — Sectional  view  of  a  double-acting  hydraulic  ram. 


The  Double-acting  Hydraulic  Ram. — The  diagram  of  Fig.  142 

I  illustrates  the  working  principle  of  the  double-acting  hydraulic 

ram  mentioned  above;  where  the  water  from  a  muddy  stream  is 

used  to  drive  the  ram  and  that  from  a  separate  source,  as  a  spring 

is  delivered. 

The  construction  of  the  double-acting  ram  is  similar  to  the 
single-acting  ram,  but  a  separate  pipe  S  discharges  spring  water 
directly  below  the  valve  which  acts  just  as  though  it  had  entered 
at  the  drive  pipe.  The  ram  in  this  case  is  receiving  water  from 
the  drive  pipe  D,  which  operates  the  valve  and  furnishes  power 
for  elevating  the  spring  water.  The  spring  water  enters  the 
ram  through  the  pipe  S,  to  keep  the  space  T  filled,  directly  under 
the  valve.  The  water  which  enters  the  air  chamber  is,  therefore, 
only  that  from  the  spring. 

A  standpipe  is  arranged  as  shown  in  the  figure,  with  a  check 


158  MECHANICS  OF  THE  HOUSEHOLD 

valve  to  prevent  the  water  in  the  ram  from  being  forced  back 
into  the  spring  water  pipe  after  entering  the  ram. 

DOMESTIC  WATER-SUPPLY  PLANTS 

Until  recent  years,  no  thought  was  given  to  private  water- 
supply  plants,  in  any  except  the  more  pretentious  residences. 
It  was  formerly  supposed  that  the  cost  of  machinery  and  instal- 
lation of  such  plants  prohibited  the  use  of  a  water  system  in  the 
average  home.  As  an  item  of  expense  in  building,  a  satisfactory 
water-supply  system  may  be  installed  at  a  lower  cost  than  is 
paid  for  plumbing  and  bathroom  fixtures. 

In  recent  years  much  attention  has  been  given  to  the  design 
of  small  water-supply  plants  for  isolated  homes,  such  as  are 
required  for  suburban  and  rural  dwellings,  with  the  result  that 
the  necessary  apparatus  to"  suit  any  conditions  may  be  obtained 
of  any  enterprising  dealer. 

The  degree  of  completeness  with  which  the  plant  is  to  be 
arranged  will  depend  on  the  funds  to  be  expended,  but  in  the  most 
modest  dwelling  some  form  of  water-supply  plant  is  possible. 
Where  opportunity  is  given  to  make  the  plant  complete,  its 
appointments  of  construction  may  be  elaborated  to  almost  any 
extent.  A  suburban  or  country  residence  may  be  made  as 
perfect  in  point  of  toilet,  kitchen  and  laundry  conveniences,  as 
where  city  water  and  sewer  service  are  available.  The  water- 
supply  plant  may  be  operated  by  hand  or  by  power,  and  if  so 
desired  may  be  made  completely  automatic  in  action. 

Gravity  Water-supply  Plant. — In  point  of  simplic'ty,  the  plant 
shown  in  Fig.  143  represents  a  water  system  that  answers  every 
purpose  of  a  cottage  and  yet  is  only  an  elevated  tank  for  storage 
of  water,  combined  with  a  house  force  pump.  The  tank  in  this 
case  may  be  made  of  wood  or  metal  and  is  open  at  the  top.  The 
water  is  sent  into  the  tank  by  the  pump,  and  gravity  furnishes 
the  force  for  carrying  it  to  the  fixtures  in  the  kitchen  and 
bathroom. 

In  using  a  tank  of  the  kind  shown  in  the  drawing,  provision 
should  be  made  for  the  possibility  of  leakage.  This  is  arranged 
for  by  having  the  tank  set  in  a  shallow  pan,  so  constructed  that 
in  case  of  accident  the  water  may  be  carried  away  without  doing 


WATER  SUPPLY 


159 


damage.  This  type  of  plant  is  not  usually  employed  in  cold 
climates,  unless  some  provision  is  made  to  prevent  the  water  in 
the  tank  from  freezing.  Tanks  of  this  kind  are  sometimes  used 
in  cold  climates  but  a  much  more  desirable  plant  for  the  purpose 
is  described  below.  In  Fig.  143  the  water  from  the  cistern  W  is 
raised  by  the  pump  P,  which  also  forces  it  into  the  tank  above 
the  kitchen.  The  gravitational  force  given  the  water,  because 


FIG.   143. — Sectional  view  of  a  cottage  containing  a  simple  gravity  water-supply 

plant. 

of  its  elevated  position  is  all  that  is  necessary  to  carry  the  water 
to  the  fixtures  in  the  bathroom  and  kitchen  sink.  As  shown  in 
the  drawing,  it  furnishes  a  complete  water  system  that  will 
perform  all  of  the  requirements  of  water  distribution  for  a  small 
family. 

The  pipes  from  the  range  boiler  are  attached  to  the  water 
heater,  which  forms  a  part  of  the  kitchen  range  as  explained  on 
pages  116  to  120.  It  receives  the  supply  of  cold  water  directly 
from  the  tank  through  the  pipe  marked  C,  and  £he  hot  water 
from  the  range  boiler  is  supplied  through  the  pipe  H .  Cold  water 
is  also  taken  from  the  tank  directly  to  each  of  the  cold-water  taps. 


160  MECHANICS  OF  THE  HOUSEHOLD 

The  pump  P  is  a  house  pump,  such  as  is  shown  in  Fig.  130. 
It  is  a  small  force  pump,  designed  to  suit  the  conditions  of 
domestic  use  and  is  made  to  send  water  into  the  sink  or  into  the 
supply  tank  as  desired. 

Pressure -tank  System  of  Water  Supply. — The  water-supply 
plant  shown  in  Fig.  144  is  another  simple  construction,  somewhat 
more  elaborate  than  the  last,  so  arranged  that  the  danger  of 
freezing  is  practically  eliminated.  This  is  a  simple  pressure- 
tank  system  in  which  a  tightly  built  metal  water  tank  takes  the 
place  of  the  elevated  tank  of  the  previous  figure,  and  a  tank 
pump  is  used  for  lifting  and  giving  pressure  to  the  water.  It  is 
a  more  complete  plant  than  the  first  and  intended  to  accom- 
modate a  larger  dwelling.  The  drawing  shows  all  of  the  fixtures 
and  connecting  pipes  that  are  required  in  the  average  home. 
It  shows  all  of  the  appliances  for  connecting  the  pressure  tank 
and  range  boiler  with  the  wash  trays  in  the  basement,  with  all 
of  the  fixtures  in  the  .bathroom  and  with  the  fixtures  in  the 
kitchen  sink.  The  range  boiler  is  the  same  as  those  previously 
described  and  connected  to  the  heater  in  an  identical  manner. 

The  original  source  of  supply  in  this  case  is  a  cistern,  sunk 
below  the  basement  floor.  The  water  is  lifted  from  the  cistern 
by  the  pump  and  forced  into  the  pressure  tank  through  a  pipe 
near  the  bottom  where  it  furnishes  the  supply  for  the  house. 

The  pressure  tank  may  be  of  any  size  to  suit  the  requirements 
of  the  house  and  may  be  placed  in  either  a  vertical  or  horizontal 
position.  It  is  sometimes  galvanized,  as  a  precaution  against 
rust,  but  this  is  not  a  necessary  requirement.  The  pipe  which 
conveys  the  water  from  the  pump  connects  with  the  tank  near 
the  bottom.  As  the  water  enters,  the  contained  air  above  its 
surface  is  compressed  into  smaller  and  smaller  space.  The 
pressure  that  is  developed  by  the  compressed  air  furnishes 
the  force  by  which  the  water  is  driven  out  of  the  tank  and 
through  the  distributing  pipes  to  the  various  parts  of  the 
system. 

If  the  air  in  the  tank  when  empty  is  compressed  to  one-half 
its  original  volume,  then  the  gage  pressure  will  be  about  15 
pounds  to  the  square  inch;  if  the  air  is  compressed  to  one-third 
its  original  volume,  that  is,  when  the  tank  is  two-thirds  full  of 
water,  the  gage  pressure  will  be  about  30  pounds  to  the  square 


WATER  SUPPLY 


161 


inch,  which  is  enough  to  supply  water  at  any  point  of  a  two-story 
building  with  ample  force.  By  pumping  more  water  into  the 
tank,  a  pressure  of  50  or  60  pounds  may  be  obtained  without 
difficulty;  but  40  pounds  is  generally  sufficient  for  all  the  demands 
of  a  house  plant.  This  is  an  application  of  the  Boyles  law  which 
as  stated  in  text  books  of  physics  is:  "The  temperature  remaining 


Fio._.144. — The  pressure- tank  system  of  water  supply  as  it  appears  in  a  dwelling. 

the  same,  the  pressure  on  confined  gas  varies  inversely  as  its 
volume."  As  the  volume  of  such  a  confined  body  of  gas  is  made 
smaller,  the  pressure  increases  in  like  ratio.  The  desired  pres- 
sures are  easily  attained  with  a  hand  force  pump  such  as  is  shown 
in  the  drawing. 

The  gage-glass  G  on  the  side  of  the  tank  is  intended  to  show 
11  i 


1G2 


MECHANICS  OF  THE  HOUSEHOLD 


the  height  of  the  water  in  the  tank  at  any  time,  and  the  pressure 
gage  attached  to  the  supply  pipe  shows  the  amount  of  pressure 
sustained  by  the  water. 

The  Pressure  Tank. — The  water  leaves  the  tank  by  a  pipe 
attached  near  the  bottom  and  branches  to  supply  each  fixture, 
to  which  the  water  is  to  be  conducted.  In  the  drawing,  the  pipe 
may  be  traced  from  the  point  where  it  leaves  the  tank  to  the  vari- 
ous fixtures.  The  cold-water  pipe  terminates  at  the  range  boiler, 
for  at  that  point  the  hot-water  system  begins.  The  range  boiler 
is  connected  by  two  pipes  to  the  water  heater  in  the  kitchen 
range.  The  water  heater  is  a  part  of  the  fire-box  of  the  kitchen 

range  and  so  long  as  the  fire  is  kept 
burning,  water  is  heated  and  stored 
in  the  range  boiler.  Where  the 
house  is  furnace-heated,  the  furnace 
fire  is  sometimes  utilized  for  heat- 
ing the  water  by  use  of  a  coil  of  pipe 
above  the  fire  and  which  may  take 
the  place  of  the  range  heater.  Vari- 
ous other  means  are  also  employed 
for  heating  the  water  as  described 
under  range  boilers.  In  Fig.  145  is 
shown  a  nearer  view  of  a  pressure 
tank  with  the  pump  attached.  The 
pump  is  in  this  case  identical  in  its 
FIG.  145.— The  pressure  tank  action  to  the  one  shown  in  Fig.  132, 

complete,  wtih  the  pump  and  but  differs  slightly  in  mechanical-  de- 
gages  as  used  for  domestic  water  .  . 

supply.  sign.     The  drawing  shows  the  gage- 

glass  G,  for  indicating  the  height  of 

water;  the  pressure  gage  P,  which  indicates  the  pressure  to 
which  the  water  is  subjected;  the  attachment  of  the  supply 
pipe  S,  and  the  delivery  pipe  D.  The  water  tap  T  is  provided 
to  draw  off  the  water  when  the  tank  is  to  be  emptied. 

In  operation,  the  air  in  the  pressure  tank  furnishes  the  force 
which  sends  the  water  through  the  pipes  to  the  various  points, 
and  forces  it  through  the  taps  at  the  desired  rate.  If  for  any 
reason  the  air  in  the  tank  escapes,  the  propelling  force  is  de- 
stroyed. This  may  occur  by  reason  of  absorption  of  the  air  by 
the  water,  due  to  the  pressure  to  which  it  is  subjected;  or  to 


WATER  SUPPLY 


163 


small  air  leaks  that  may  develop  in  the  joints,  which  allow  the 
air  to  escape.  To  overcome  the  possibility  of  these  occurrences, 
arrangement  is  made  whereby  air  may  be  pumped  into  the  tank 
by  the  same  pump  as  that  which  supplies  the  water.  In  this 
way,  the  air  is  introduced  with  the  water,  which  bifbbles  up 
through  it  to  the  surface.  If  at  any  time  the  pressure  in  the  tank 
is  lost,  it  may  be  replaced  by  pumping  air  alone  into  the  tank. 

Power  Water-supply  Plants. — Where  the  pump  is  expected 
to  furnish  water  to  any  considerable  amount  beyond  that  for 
household  use,  it  is  desirable  that  the  plant  be  power-driven. 
If  the  work  of  watering  stock,  lawn  sprinkling,  etc.,  is  intended, 


FIG.   146. — Tank  pump  operated  by  a  small  gasoline  engine. 

the  tank  and  pump  must  be  enlarged  to  suit  the  desired  amount 
of  water,  and  a  gasoline  engine,  windmill  or  electric  motor  will 
be  used  for  power.  Where  local  conditions  will  permit,  a 
hydraulic  ram  may  be  substituted  for  the  pump  and  the  pressure 
tank  used  for  additional  pressure  and  storage. 

Fig.  146  shows  a  plant  in  which  the  pump  is  driven  by  a 
gasoline  engine.  In  the  figure,  the  engine  E  is  shown  connected 
by  a  belt  to  a  speed-reducing  device  or  "jack,"  marked  J.  The 
object  of  this  machine  is  to  reduce  the  speed  of  rotation  and 
charge  it  to  the  required  motion  for  operating  the  pump.  The 


164 


MECHANICS  OF  THE  HOUSEHOLD 


jack  is  connected  to  the  pump  by  a  rod  attached  to  a  large  gear, 
so  as  to  produce  the  desired  crank  motion;  and  the  opposite  end 
of  the  rod  is  attached  to  the  pump  handle.  The  rod  may  be 
detached  at  any  time  and  the  pump  worked  by  hand. 

Electric  Power  Water  Supply.—  Fig.  147  shows  another  type 
of  power  plant  in  which  an  electric  motor  operates  the  pump. 
In  this  style  of  plant,  the  pulley  on  the  electric  motor  M  is 
connected  by  a  belt  to  the  large  wheel  W,  from  which  ,the  crank 
motion  is  secured  for  driving  the  pump  P.  This  machine  is 
provided  with  an  automatic  starting  and  stopping  device,  which 

automatically  controls  the  supply 
of  water  in  the  system.  Whenever 
the  pressure  in  the  tank  falls  to  a 
certain  point,  the  change  of  pressure 
produced  on  the  diaphram  valve  A 
starts  the  motor,  and  the  pump  sends 
water  into  the  tank  until  the  pressure 
in  the  tank  again  reaches  the  amount 
for  which  the  valve  is  set,  at  which 
time  the  valve  disconnects  the  elec- 
tric contact  to  the  motor  and  the 
pump  stops  working. 

Wind  -power  Water  Supply.  —  In 
Fig.  148  is  shown  a  larger  and  more 
complete  plant  than  the  former,  in 
which  a  windmill  furnishes  the  power 
for  pumping  and  a  large  under- 
ground tank  is  utilized  for  the  main 
FIG.  147.  —  Pressure  tank  supplied  supply  of  water.  The  tank  marked, 

by  an  electrically  driven  pump.     WeR    Water    presgure   Tank?   jn  this 


case  is  so  placed  that  the  end  is  exposed  in  the  well  curb,  where 
the  height  of  the  water  may  be  observed  at  any  time.  The 
pump  is  operated  as  any  other  of  its  kind,  but  is  provided  with 
an  automatic  pressure  cylinder,  which  controls  the  operation  of 
the  mill  through  the  rise  and  fall  of  the  water  in  the  tank.  At 
any  time  the  water  in  the  tank  falls  to  a  certain  point,  the 
pump  is  thrown  into  gear  by  the  pressure  cylinder,  and  the 
water  is  pumped  into  the  tank  until  a  definite  height  is  reached; 
at  this,  point  the  pump  is  automatically  thrown  out  of  gear  and 


WATER  SUPPLY 


165 


remains  inactive  until  an  additional  supply  of  water  is  required. 
The  plant  is  therefore  automatic  in  its  action  and  requires  only 
that  the  mill  be  kept  oiled  and  in  running  order. 

As  shown  in  the  drawing,  the  large  tank  receives  its  supply  of 
water  from  the  well  and  aside  from  providing  a  reserve  supply 
furnishes  power  for  pumping  cistern  water.  The  water  from 
the  large  tank  is  piped  into  the  house  for  use  as  required,  and  from 


FIG.  148. — This  diagram  shows  the  arrangement  of  domestic  water-supply 
apparatus,  in  which  a  windmill  furnishes  the  pressure  necessary  for  operating 
the  entire  plant. 

the  same  pipe  is  taken  a  hydrant  for  lawn  sprinkling;  in  addition, 
this  water  is  piped  to  the  barn  where  it  is  used  for  watering  stock. 
A  branch  of  the  same  pipe  is  intended  to  operate  a  water  lift, 
which  in  turn  furnishes  the  house  with  soft  water  from  the  rain- 
water cistern  for  bathing,  laundry,  and  kitchen  purposes. 

The  Water  Lift. — The  water  lift  is  a  combined  water  engine 
and  pump,  the  motive  power  for  which  is  the  pressure  from  the 


166  MECHANICS  OF  THE  HOUSEHOLD 

well-water  tank.  The  soft  water,  pumped  by  the  water  lift, 
is  stored  in  the  smaller  pressure  tank  marked  Soft  Water  Pressure 
Tank  in  the  drawing,  and  furnishes  a  supply  for  the  purposes 
mentioned.  The  water  lift  is  so  constructed  that  when  the 
pressure  in  the  soft-water  tank  equals  the  pressure  in  the  well- 
water  tank,  the  lift  will  stop  working  and  will  not  start  again 
until  water  has  been  drawn  from  the  taps.  Whenever  water  is 
drawn  from  any  part  of  the  system,  the  pressure  will  be  reduced 
and  the  lift  will  immediately  begin  pumping  more  water  and  will 
continue  until  the  pressure  of  the  two  tanks  are  the  same.  The 
system  is  entirely  automatic,  each  part  depending  on  the  power 


INLET  I 


'USTABLE 
REGULATOR. 


DISCHARGE: 


WASr£ 

FIG.  149.— The  water  lift. 

originally  supplied  by  the  windmill.  The  plant  could  be  just  as 
successfully  operated  by  substituting  a  gasoline  engine  or  other 
source  of  power  for  the  windmill.  The  machinery  for  such  a 
plant  is  not  at  all  complicated  neither  is  it  difficult  to  manage, 
yet  it  is  complete  in  every  particular  and  furnishes  an  almost 
ideal  arrangement  for  a  country  or  suburban  home. 

In  order  to  be  assured  of  a  supply  of  water  over  periods  of 
atmospheric  quiet,  the  well-water  tank  must  be  sufficiently 
large  to  supply  water  for  3  or  4  days;  but  in  case  of  emergency 
water  may  be  pumped  by  hand. 

A  nearer  view  of  the  water  lift  is  shown  in  Fig.  149.     In  the 


WATER  SUPPLY 


167 


figure,  the  right-hand  cylinder  with  its  valve  V  is  the  water 
engine  which  furnishes  the  power  for  operating  the  pump,  en- 
closed in  the  left-hand  cylinder.  The  water  pressure  of  the 
main  supply  furnishes  the  energy  which  drives  the  engine,  the 
piston  rod  of  which  is  attached  to  the  pump  piston.  The  engine 
receives  its  supply  of  water  through  the  pipe  marked  Inlet  and 


1  Air  Chamber  Nut 

2  Brass  Tube  for  Air 
Chamber 

3  Air  Chamber 

4  Brass  Cock 

5  Cap  Screw 

6  Leather  Washer 

7  Handle  Pin 

8  Pitman 

9  Handle  « 

10  Brass  Covered 
Piston  Rod 

11  Fulcrum 

12  Fulcrum  Pin 

13  Brass  StuJing  Nut 


14'Cap 

15  Fulcrum  Ring 

16  Fulcrum  Ring 
Pin 

f!7  Plunger 
13  Cylinder 


19  Cap  Screw 

20  Lower  Valve 

21  Brass  Valve 
Seat 

22  Base 
Bottom  Brass 
Ferrule 

24  Bottom  Kut 


FIG.   150. — The  terms  by  which  the  parts  of  a  force  pump  are  designated. 

the  waste  water  is  discharged  to  the  sewer  by  the  waste  pipe  on 
the  opposite  side  of  the  cylinder.  The  operation  of  the  lift  is  gov- 
erned by  an  automatic  regulator  which  so  controls  the  engine 
that  it  starts  pumping  whenever  the  pressure  in  the  system  falls 
to  a  certain  point.  The  regulator  marked  Adjustable  Regulator 
in  the  drawing  may  be  adjusted  to  suit  the  water  pressure  desired 
in  the  distributing  system. 


CHAPTER  VIII 
SEWAGE  DISPOSAL 

The  disposal  of  sewage,  in  a  convenient  and  sanitary  manner 
is  a  problem  of  serious  importance  in  the  equipment  of  isolated 
dwellings  with  modern  household  conveniences.  The  manner  of 
heating,  lighting  and  of  water  supply  are  questions  of  selection 
among  a  number  of  established  systems,  but  the  problem  of  sew- 
age disposal  must  in  a  great  measure  be  determined  by  local 
conditions.  Unless  the  natural  surroundings  are  such  as  will 
permit  sewage  to  be  emptied  directly  into  a  stream  of  considerable 
volume,  the  problem  of  its  safe  disposal  becomes  one  of  serious 
importance. 

Sewage  is  understood  to  mean  the  fluid  waste  from  the  kitchen, 
toilet  and  laundry  and  has  nothing  whatever  to  do  with  garbage. 
Sewage  disposal  has  to  do  with  conducting  away  the  house 
waste  and  disposing  of  it  in  a  sanitary  manner.  Sewage  disposal 
does  not  necessarily  have  anything  to  do  with  sewage  purifica- 
tion ;  although  a  sewage  disposal  plant  may  be  so  constructed  as 
to  discharge  a  purified  effluent,  it  usually  is  understood  to  have 
to  do  alone  with  its  disposal  in  a  manner  that  does  not  offend 
the  aesthetic  sense.  A  simple  sewage  plant  is  anything  that 
will  take  the  sewage  away  from  the  house  in  such  a  way  as  to 
produce  no  unsightly  accumulations  that  will  decay  and  produce 
offensive  odors. 

A  sewage  purification  plant  is  one  in  which  the  raw  sewage  from 
the  house  drain  is  first  liquefied,  after  which  the  liquid  is  passed 
into  a  filter  where  it  undergoes  a  process  of  bacterial  disintegra- 
tion and  the  organic  matter  reduced  to  the  inorganic  state,  where 
no  further  change  is  possible.  The  water  which  flows  from  such 
a  filter  is  clear  and  sparkling,  and  is  often  taken  for  spring  water. 
The  degree  of  purification  given  to  the  sewage  will  depend  on 
the  style  of  filter  and  the  length  of  time  necessary  for  the  water 
to  pass  through  it. 

168 


SEWAGE  DISPOSAL  169 

Sewage  is  composed  of  organic  matter  in  a  fluid  or  part  fluid 
condition,  contained  in  a  large  volume  of  water.  It  is  not  usually 
the  dark,  heavy,  foul-smelling  fluid  that  is  imagined  by  many, 
but  a  turbid  liquid  possessing  only  a  few  of  the  qualities  usually 
ascribed  to  sewage.  Under  favorable  conditions  practically 
all  of  the  organic  matter  will  be  readily  dissolved  and  the  sewage 
will  become  entirely  liquid. 

As  a  liquid,  the  raw  sewage  is  in  the  most  favorable  condition 
for  rapid  decay  and  if  left  standing  in  the  air  it  soon  develops 
properties  that  render  it  highly  objectionable. 

The  decay  of  all  organic  matter  is  a  process  of  disintegration 
that  ultimately  ends  in  the  elements  from  which  it  came.  In  the 
disposal  of  sewage,  the  aim  is  to  permit  this  disintegration  to 
take  place  under  conditions  that  will  be  least  offensive  to  the 
aesthetic  sensibilities,  and  in  some  cases  to  render  it  free  from 
harmful  properties  should  there  be  present  the  bacteria  of  com- 
municable disease. 

The  successful  disposal  of  sewage  from  cities  is  accomplished 
under  a  great  variety  of  conditions.  It  is  much  easier  to  arrange 
for  sewage  purification  on  a  large  scale  than  in  a  small  way. 
The  reason  for  this  is  that  in  the  care  of  a  city  the  sewage-disposal 
plant  is  under  the  supervision  of  a  competent  person,  whose 
business  it  is  to  see  that  the  conditions  are  kept  at  the  highest 
efficiency.  Private  plants  are  left  almost  entirely  without  care, 
until  they  fail  from  causes  that  are  usually  preventable.  Sewage 
may  be  successfully  purified  under  a  great  many  conditions, 
but  no  type  of  plant  has  as  yet  proven  itself  successful  that  does 
not  receive  intelligent  attention. 

The  most  successful  of  small  sewage  disposal  plant  is  the 
septic  tank  system  alone  or  in  connection  with  an  adequate 
form  of  bacterial  filter.  Cesspools  are  not  to  be  countenanced 
by  people  of  intelligence.  The  cesspool  has  been  so  universally 
condemned  by  authorities  on  sanitation,  that  all  intelligent 
people  look  upon  it  as  a  thing  filthy  beyond  description.  Al- 
though the  septic  tank  is  little  more  than  an  improved  cess- 
pool, the  condition  under  which  it  acts  is  entirely  different 
from  that  which  takes  place  in  the  latter  and  with  care 
and  watchfulness,  it  may  be  made  to  work  to  a  degree  of 
perfection  that  is  surprising.  The  one  great  cause  of  the 


170  MECHANICS  OF  THE  HOUSEHOLD 

failure  of  small  sewage-disposal  plants  is  the  lack  of  proper 
care. 

The  process  of  sewage  purification  as  now  practised  in  the 
most  successful  plants  is  largely  mechanical,  but  bacterial  ac- 
tion plays  a  part  of  great  importance  in  the  completion  of 
the  process.  It  consists  of  two  stages:  the  tank  treatment, 
in  which  the  sewage  is  liquefied;  and  the  process  of  filtration 
where  the  liquefied  sewage — commonly  called  the  effluent— 
from  the  septic  tank  undergoes  a  process  of  filtration  and 
bacterial  purification. 

The  Septic  Tank. — The  septic  tank  alone,  as  used  for  sewage 
disposal,  is  often  termed  a  sewage  purifying  plant,  when  in  reality 
it  is  only  intended  to  change  the  sewage  into  a  form  in  which  it  can 
be  readily  carried  away.  The  word  septic  means  putrifying, 
and  when  applied  to  sewage  disposal  it  furnishes  a  convenient 
term  but  has  nothing  to  do  with  purification.  The  septic  tank 
furnishes  only  the  first  stage  of  the  purifying  process,  and  al- 
though its  effluent  may  be  clear  and  possess  little  odor,  it  is 
nevertheless  unpurified.  The  septic  tank  discharges  an  effluent 
of  more  or  less  completely  digested  sewage,  instead,  as  in  the 
cesspool,  of  permitting  it  to  remain  a  constantly  festering  mass, 
to  be  slowly  absorbed  by  the  earth. 

The  sewage  is  first  collected  in*a  tank  of  sufficient  size  to  con- 
tain the  discharge  from  the  house  for  24  hours.  In  the  process 
of  digestion  which  ^he  sewage  undergoes  while  in  the  tank,  it  is 
rendered  almost  entirely  liquid ;  at  the  same  time  it  is  acted  upon 
by  the  bacteria  that  are  developed,  and  that  tend  to  reduce  the 
sewage  to  its  elemental  form.  The  effluent  liquid  which  passes  out 
of  the  tank  is  almost  colorless  and  possesses  relatively  little  odor. 

The  tendency  of  the  change  which  takes  place  in  the  tank  is 
to  nitrify  the  organic  matter  but  under  ordinary  conditions  the 
action  is  not  fully  complete.  The  effluent  sometimes  undergoes 
but  little  change  except  to  be  reduced  to  a  liquid.  If  the  effluent 
is  now  allowed  to  flow  into  a  ditch  where  it  will  stand  in  pools, 
further  purification  will  take  place  with  its  resulting  annoyance. 
In  case  the  septic  tank  is  to  be  used  alone,  the  effluent  should  be 
conducted  to  a  stream  for  final  disposal.  A  septic  tank  must  be 
built  to  accommodate  a  certain  number  of  people  and  of  sufficient 
size  to  take  care  of  the  entering  sewage.  The  action  which  goes 


SEWAGE  DISPOSAL  171 

on  in  the  tank  will  render  the  contents  almost  entirely  fluid,  and 
under  good  conditions  the  sewage  will  be  completely  digested. 
When  working  properly,  a  thick  scum  will  form  on  the  surface, 
through  which  niters  the  gases  that  are  liberated  in  the  process 
of  disintegration.  The  formation  of  the  scum  is  an  indication 
that  the  filter  is  doing  its  best  work.  Should  the  tank  be  re- 
quired to  take  care  of  more  sewage  than  it  can  conveniently 
handle,  the  scum  will  not  form  and  the  effluent  will  be  turbid 
because  of  the  undigested  matter. 

The  change  that  takes  place  in  the  sewage  while  it  remains  in 
the  tank  is  first  that  of  being  liquefied  and  then  disintegrated  by 
bacterial  action.  That  such  a  change  does  take  place  is  evi- 
denced by  the  residue  that  is  found  in  the  tank  in  the  process  of 
cleaning.  This  is  a  black  granular  substance,  composed  mostly 
of  humus  and  commonly  known  as  sludge.  The  amount  of 
accumulated  sludge  is  relatively  small,  and  the  operation  of  clean- 
ing is  not  necessary  more  than  twice  a  year  and  is  not  the  dis- 
agreeable task  one  might  suppose. 

The  Septic  Tank  With  a  Sand-bed  Filter.— In  places  where 
the  use  of  the  septic  tank  alone  is  not  possible,  it  sometimes 
happens  that  the  natural  conditions  are  such  as  will  permit  the 
effluent  to  be  drained  directly  into  the  soil.  With  such  a  con- 
dition, the  effluent  goes  into  a  filter  bed  composed  of  gravel  or 
other  loose  material,  where  it  undergoes  still  further  bacterial 
action  and  if  the  process  is  complete,  the  water  which  comes 
from  the  filter  bed  is  clear  and  odorless.  Under  good  conditions 
it  is  clear  sparkling  water  and  contains  but  a  small  amount  of 
impurities. 

Septic  tanks  are  made  in  many  forms  but  that  illustrated  in 
Figs.  151  and  152  is  commonly  used.  In  Fig.  151  the  tank  is 
shown  in  position  to  receive  the  sewage  from  the  house  drain, 
where  it  is  to  undergo  the  first  treatment  and  then  to  be  con- 
ducted to  a  filter  bed  made  of  porous  tile,  set  in  loose  soil.  The 
tank  is  shown  in  detail  in  Fig.  152.  It  is  a  cemented  brick 
cistern  with  an  opening  to  the  surface  that  contains  a  double 
cover  as  a  protection  during  cold  weather.  A  brick  partition 
divides  the  tank  into  spaces  G  and  H,  that  contain  volumes  that 
are  to  each  other  as  1  to  2.  The  tank  is  of  such  size  as  will  hold 
a  volume  of  sewage  equal  to  24  hours'  use;  that  is,  it  is  expected 


172 


MECHANICS  OF  THE  HOUSEHOLD 


that  any  portion  of  sewage  will  remain  in  the  tank  for  that  length 
of  time.  The  sewage  enters  at  A,  in  such  a  way  as  will  give  the 
least  disturbance  of  the  liquid  of  the  tank.  An  opening  C  allows 
the  liquid  to  pass  from  H  into  G,  where  any  additional  sewage 
entering  H  will  displace  an  equal  amount  in  G,  which  will  pass 
out  at  B  to  the  filter  bed.  The  partition  D  is  high  enough  so 
that  the  scum  that  forms  on  the  surface  will  not  pass  directly 
into  the  space  G.  The  entrance  and  exit  pipes  are  made  of 
vitrified  sewer  tile  with  the  openings  below  the  surface. 


•^K^*t*^,\1,-.-      House  Drain 


FIG.   151. — Sectional  view  of  a  septic  tank,  connected  with  a  sand-bed  filter;  for 
the  disposal  of  sewage  from  a  residence. 

As  the  sewage  enters  the  tank  A}  a  considerable  portion  will 
sink  to  the  bottom,  while  some  will  float  to  the  top  where  a  thick 
scum  will  gather.  By  far  the  greatest  portion  of  solids  will  be 
readily  dissolved  in  the  water  and  the  remainder  will  be  still 
further  reduced  to  liquid  form  by  bacterial  solution.  The  process 
of  disintegration  that  goes  on  evolves  a  considerable  amount  of 
carbon  dioxide  and  ammonia  which  filters  through  the  scum. 
The  process  that  now  goes  on  in  the  tank  is  that  of  liquefying  the 
organic  matter  and  changing  it  from  organic  to  the  inorganic 
state. 

The  bacteriologist  recognizes  in  the  process  of  sewage  disin- 
tegration the  work  of  two  classes  of  bacteria,  the  aerobic  or  those 


SEWAGE  DISPOSAL 


173 


bacteria  that  work  by  reason  of  air  and  do  their  work  only  in  its 
presence  and  the  anaerobic  or  those  that  work  in  the  absence  of 
air.  In  the  action  of  the  sewage-disposal  plant  both  kinds  of 
bacteria  are  at  work.  If,  in  the  final  stage  where  the  sewage 
passes  into  the  filter,  air  can  be  carried  into  the  earth  the  action 
will  be  hastened. 

It  is  evident  that,  since  the  sewage  entering  the  tank  is 
almost  entirely  dissolved,  under  ideal  action  this  system  would 
give  very  little  trouble,  but  actually  as  the  sewage  enters  the 


FIG.   152. — Section  of  the  septic  tank  in  Fig.  151  showing  details  of  construction. 

tank  the  disturbance  caused  by  the  incoming  water  forces  some 
of  the  undigested  matter  into  the  outlet  and  being  carried  into 
the  filter  bed  it  will  be  deposited  at  the  first  opportunity.  This 
will  cause  the  filter  bed  to  fill  up  with  undigested  sewage  at  the 
point  nearest  the  entrance,  and  in  course  of  time  it  will  stop  the 
pipe  because  of  this  accumulation. 

To  avoid  such  an  occurrence,  tanks  have  been  built  in  which  an 
automatic  siphon  discharges  the  effluent  whenever  a  certain 
quantity  has  collected.  Such  a  tank  is  shown  in  Fig.  153.  With 
this  arrangement,  the  sewage  enters  the  first  tank  at  A,  and  passes 


174 


MECHANICS  OF  THE  HOUSEHOLD 


into  the  second  tank  at  B.  At  S  is  shown  an  automatic  siphon, 
so  made  that  when  the  effluent  has  collected  to  the  height  of  the 
water  line,  the  siphon  automatically  discharges  the  contents  of 
the  tank.  This  is  known  as  a  dosage  tank  because  periodically 
a.  dose  of  the  effluent  is  discharged  into  the  filter  bed.  The 
volume  discharged  is  sufficient  to  fill  the  greater  portion  of  the 
bed,  and  force  out  the  air  in  the  loose  soil.  As  the  water  filters 
from  the  bed  the  air  is  drawn  in  to  take  its  place  and  gives  the 
bacteria  which  work  in  the  presence  of  air  an  opportunity  to 
do  their  work.  The  work  done  by  this  filter  bed  is  first  to  filter 
out  any  suspended  matter  carried  in  the  effluent  which  will  lodge 
on  the  surface  of  the  filter  material  and  then  to  undergo  the  slow 


FIG.   153. — Sectional  view  of  a  two-chamber  septic  tank  with  a  dosage  siphon. 

process  of  integration,  and  to  permit  the  oxidation  of  the  dis- 
solved sewage.  If  this  matter  is  deposited  faster  than  it  dis- 
integrates then  the  filter  will  fill  up  and  finally  refuse  to  work. 

The  Septic  Tank  and  Anaerobic  Filter. — In  places  where  the 
use  of  the  simple  septic  tank  is  not  possible  and  where  the  char- 
acter of  the  soil  will  not  permit  of  a  natural  sand-bed  filter,  an 
anaerobic  filter  may  be  constructed  through  which  to  pass  the 
effluent  from  the  septic  tank. 

The  anaerobic  filter  is  one  in  which  anaerobic  bacterial  action 
is  given  opportunity  to  reduce  the  organic  matter  in  the  sewage 
to  its  elemental  condition.  The  filter  may  be  constructed  in  any 
form  that  will  permit  the  process  of  filtration  to  be  carried  out 
in  a  way  that  will  afford  good  anaerobic  action.  The  extent  to 


SEWAGE  DISPOSAL 


175 


which  the  purification  is  to  be  carried  will  determine  the  form  and 
size  of  the  filter. 

In  Fig.  154  is  shown  such  a  plant,  where  a  combined  septic  tank 
and  anaerobic  filter  discharges  its  effluent  into  a  filter  ditch  in 
which  the  purifying  process  is  continued  through  a  bed  of  gravel 
of  any  desired  length.  The  figure  illustrates  a  plant  that  was 
designed  for  a  country  residence.  The  septic  tank  and  anaerobic 
filter  are  located  relatively  as  shown  in  the  drawing,  the  filter 
ditch  following  the  course  of  a  roadway.  The  water  is  finally 
discharged  into  a  little  stream,  where  it  mingles  with  the  water 
from  a  spring,  and  flows  through  a  meadow. 


Longitudinal  Section  of  Anaerobic  Filter 


SEPTIC  TANK 

AND 
ANAEROBIC  FILTER 

General  Arrangement  of  Plant 
FIG.   154. — Sectional  view  of  a  septic  tank  combined  with  an  anaerobic  filter;  to- 
gether with  the  details  of  construction  and  plan  of  arrangement. 

The  septic  tank  in  Fig.  154  is  quite  similar  in  construction  to  the 
others  described  except  that  a  section  of  sewer  tile  takes  the  place 
of  the  brick  wall  between  the  two  parts  of  the  tank.  The  opening 
0,  through  which  the  effluent  is  discharged,  is  located  a  little 
above  the  center  of  the  tank. 

The  anaerobic  filter  is  a  tank,  rectangular  in  cross-section, 
made  with  brick  walls  and  cemented  on  the  inside.  The  effluent 
from  the  septic  tank  enters  the  anaerobic  filter  in  a  chamber,  that 
is  separated  from  the  main  tank  by  a  wooden  grating  against 
which  rests  the  filter  material.  As  indicated  in  the  drawing,  the 
bottom  is  filled  with  coarse  material;  stones  or  broken  tiles 


176  MECHANICS  OF  THE  HOUSEHOLD 

about  4  inches  in  diameter.  Above  this  is  a  layer  of  material 
about  2  inches  in  diameter  and  above  that  another  layer  of  1-inch 
material;  the  top  is  made  of  gravel.  This  forms  the  anaerobic 
filter,  in  which  takes  place  the  bacterial  action  away  from  the 
presence  of  air.  The  interspaces  in  the  filter  material  allows  the 
effluent  from  the  septic  tank  to  seep  through  and  deposit  the 
particles  of  matter  held  in  suspension.  The  arrangement  is 
such  as  is  best  suited  to  the  anaerobic  action.  Here,  shut  away 
from  the  light  and  air,  the  organic  matter  in  the  effluent  under- 
goes disintegration  just  as  would  happen  in  the  earth. 

It  is  evident  that  some  of  the  matter  that  should  remain  in  the 
septic  tank  and  be  removed  as  sludge  will  be  carried  into  the 
anaerobic  filter.  This  will,  of  course,  form  an  insoluble  deposit 
that  will  accumulate  and  in  the  course  of  time  the  filter  will  be- 
come clogged.  It  should  be  expected  that  such  a  filter  will  ulti- 
mately need  renewing,  for  this  reason  the  top  is  made  of  a  slab  of 
reinforced  concrete  that  may  be  raised  to  allow  the  removal  and 
refilling  of  the  filter  material. 

The  automatic  siphon  discharges  the  water  from  the  chamber 
S,  whenever  it  fills.  The  discharged  water  from  the  siphon  is 
conducted  into  a  drain  tile,  placed  in  a  ditch  filled  with  gravel  or 
other  loose  material,  which  serves  as  an  additional  filter  and  in 
which  the  water  undergoes  a  still  further  purification.  This  filter 
ditch  is  constructed  as  indicated  in  longitudinal  section.  The 
water  from  the  siphon  enters  the  tile  C  and  seeping  through  the 
filling  is  drained  away  in  the  tile  shown  at  D. 

The  tiles  are  not  set  close  together,  but  the  joints  are  left  open 
and  covered  by  pieces  of  broken  tile  as  shown  in  H.  This  is  to 
prevent  the  filter  material  from  entering  the  tile  and  thus  stop- 
ping the  ready  flow  of  the  water. 

The  filter  ditch  of  the  plant  will  be  constructed  according  to 
the^ontour  of  the  ground  and  will  follow  the  natural  drainage. 
The*  course  of  the  ditch — if  it  is  desired  to  use  one — will  accom- 
modate itself  to  the  character  of  the  ground.  The  final  discharge 
of  the  water  will  be  determined  by  the  natural  drainage. 

That  a  plant  of  this  kind  will  work  perfectly  when  new  is 
is  beyond  a  doubt  but  that  it  will  continue  indefinitely  to  give 
perfect  satisfaction  is  not  reasonable  to  expect.  The  septic  tank 
will  require  cleaning,  probably  once  a  year.  The  anaerobic  filter 


SEWAGE  DISPOSAL 


177 


will  require  renewing  at  intervals,  depending  on  the  amount  of 
sewage  the  filter  is  required  to  take  care  of  and  the  rate  at  which 
the  plant  is  worked,  probably  once  in  4  or  5  years.  If  the  septic 
tank  is  of  insufficient  size  to  readily  digest  the  sewage,  the  ac- 
cumulation of  sludge  in  the  anaerobic  filter  will  be  greater  than 
should  occur. 

It  would  be  only  reasonable  to  suppose  that  the  siphon  will 
sometimes  refuse  to  discharge. 
Even  though  it  is  an  automatic 
siphon,  circumstances  may  cause  it 
at  times  to  fail  to  act.  For  this 
reason  the  manhole  is  placed  so 
that  the  siphon  may  be  inspected 
and  repaired,  should  it  be  necessary. 
It  must  not  be  supposed  that  once 
such  a  plant  is  in  place  that  all  of 
the  work  is  over.  The  success  of 
a  good  sewage-disposal  plant  of  this 
kind  demands  eternal  vigilance. 

In  the  level  areas  where  the 
possibilities  of  natural  drainage  is 
not  good,  it  sometimes  occurs  that 
plants  such  as  those  described  are 


FIG.   155. — Septic  tank  with  a  settling  basin  and  windmill  pump. 

not  permissible.  To  overcome  such  conditions  the  plant  in 
Fig.  155  represents  an  installation  where  the  effluent  is  carried 
several  hundred  feet  through  a  drain  tile  before  it  is  finally  dis- 
charged into  an  outlet.  This  plant  is  made  up  of  two  separate 
tanks,  the  first  acting  as  a  septic  tank,  while  the  second  tank  is 
a  settling  chamber.  The  water  from  the  second  chamber  is 
12 


178  MECHANICS  OF  THE  HOUSEHOLD 

pumped  by  windmill  power  and  discharged  into  a  drain  tile  at 
the  required  height  through  which  it  is  carried  to  the  place  of 
final  deposit. 

Limit  of  Efficiency. — Much  that  has  been  written  on  the 
subject  conveys  the  impression  that  the  septic  tank  alene,  used 
under  various  conditions,  will  eliminate  disease  germs  and  all 
offending  features  of  sewage  and  render  it  a  pure  water  with  a 
small  amount  of  residue  remaining  in  the  tank.  That  such  is 
not  the  case  is  all  too  evident  to  many  who  have  constructed 
plants  expecting  perfect  results  and  have  attained  only  partial 
success. 

It  is  not  reasonable  that  a  plant  giving  satisfaction  under  the 
usual  conditions  could  accomplish  its  purpose  under  stress  of 
work.  It  is  quite  evident  that  the  amount  of  sewage  from  any 
source  cannot  be  constant.  It  is  equally  evident  that  the  effluent 
from  the  plant  cannot  always  be  the  same;  but  with  reasonable 
limits  of  variation,  a  suitably  designed  tank  ought  to  take  care  of 
the  sewage  from  a  house  at  all  times  and  discharge  an  effluent 
that  is  reasonably  clear  and  without  offending  odor. 

It  should  be  kept  in  mind  that,  as  commonly  used,  the  chief 
office  of  the  septic  tank  is  to  do  away  with  the  things  that  offend 
the  senses,  and  not  to  make  an  effluent  that  might  serve  as  drink- 
ing water.  It  must  also  be  kept  in  mind  that  if  the  disease  germs 
enter  the  plant  because  of  sickness  in  the  house  that  there  is 
every  possibility  that  the  germs  will  be  in  the  discharged  water. 

The  plant  must  be  located  as  is  directed  by  the  natural  sur- 
roundings but  the  drainage  must  be  away  from  buildings  and 
particularly  from  wells. 

Small  sewage  plants  are  reasonably  efficient  and  add  immensely 
to  the  comfort  and  healthful  conditions  of  the  home.  They  are 
not  perfect  in  their  action  but  there  is  excellent  reason  to  believe 
that  the  plant  of  ideal  construction  will  yet  be  attained. 

In  a  flat  country  where  drainage  is  difficult,  the  form  of  plant 
must  be  modified  to  suit  the  prevailing  conditions  but  some  form 
of  working  plant  can  always  be  devised.  Small  plants  do  not 
give  so  efficient  results  as  those  of  large  size  but  they  do  very 
acceptable  work.  To  do  good  service  they  must  receive  attention 
but  the  actual  amount  of  labor  they  demand  is  small.  Small 
sewage- disposal  plants  are  not  expensive  nor  difficult  to  construct, 


SEWAGE  DISPOSAL  179 

and  for  the  amount  of  labor  and  money  expended  they  give 
returns  that  cannot  be  estimated. 

In  determining  the  character  of  plant  to  be  constructed,  in 
any  particular  place,  local  conditions  will  in  a  great  measure 
decide  the  type  to  be  used.  The  degree  of  purity  to  which  it 
will  be  necessary  to  reduce  the  effluent  will  depend  on  the  location 
of  the  plant  and  the  means  of  final  disposal.  If  the  effluent 
can  be  run  into  a  stream  of  sufficient  volume,  the  septic  tank  alone 
will  probably  answer  the  purpose. 

The  septic  tank  reduces  sewage  to  a  liquid  form  which  has  some 
odor.  It  may  be  carried  away  in  an  open  ditch  which  has  good 
flow,  but  if  allowed  to  collect  in  pools  it  will  undergo  further 
putrescence  and  be  objectionable. 

It  may  be  possible  to  use  a  small  creek  for  final  disposal  but 
one  in  which  the  effluent  from  a  septic  tank  alone  would  be  objec- 
tionable. In  such  a  case  the  use  of  the  septic  tank  combined  with 
an  anaerobic  filter  would  probably  give  a  permissible  degree  of 
purity. 

With  a  plant  composed  of  a  septic  tank  and  anaerobic  filter, 
sewage  is  rendered  almost  free  from  odor  and  the  effluent  will 
not  undergo  further  putrescence  when  collected  in  pools. 

In  many  cases  it  is  desired  to  purify  the  effluent  still  further, 
either  because  of  lack  of  means  for  final  disposal  or  because  the 
effluent  would  contaminate  the  water  into  which  it  is  discharged. 
In  such  cases  the  plant  will  consist  of  the  septic  tank,  an  anaerobic 
filter  and  a  filter  ditch  or  sand-bed  filter.  The  effluent  from  such 
a  plant  will  be  clear  sparkling  water  that  might  be  mistaken  for 
spring  water. 

The  design  and  construction  of  sewage-disposal  plants  has  been 
made  a  subject  of  investigation  in  a  number  of  State  engineer- 
ing experiment  stations.  In  addition,  manufacturers  of  cement 
have  prepared  descriptive  literature  that  is  sent  gratis  on  applica- 
tion. These  bulletins  contain  detailed  information  as  to  the 
working  properties  and  coustruction  of  private  plants  to  suit  the 
various  conditions  of  disposal.  The  following  is  taken  by  per- 
mission of  the  Universal  Portland  Cement  Co.  from  their  bulle- 
tin on  "Concrete  Septic  Tanks." 

"The  design  in  Fig.  156  shows  a  septic  tank  as  it  would  appear  if 
partly  cut  away  to  expose  the  interior  to  view,  and  as  if  cut  in  half 


180 


MECHANICS  OF  THE  HOUSEHOLD 


along  a  center  line  following  its  length.     This  type  will  be  found  to 
operate  effectively  where  final  disposal  is  accomplished  by  sub-surface 


s  Round  rods  -»  6*U  -  /iji  i 

6'ctoci'dbove  ^ 

bottom  of  ' 


No  9  Wire  6"ctoc  or  2' mesh  poultry 
netting  £  from  bottom. 


FIG.  156. — Septic  tank.  This  shows  the  construction  as  if  cut  away  along  a 
center  line  following  its  legnth,  also  a  section  of  the  siphon  chamber  and  a  plan 
of  the  whole  construction. 


•••••••••••••••^•••••••••^•ral 

FIG.   156a — Photographic    reproduction    of  a  concrete  septic  tank,  similar  to 
that  of  Fig.  153.     The  tank  requires,  only  the  cover  to  make  it  complete. 

irrigation.     This  system  once  started  is  self-operating  due  to  the  siphon 
shown  in  the  second,  or  right-hand  compartment,  which  at  regular 


SEWAGE  DISPOSAL  181 

intervals  empties  the  contents  and  discharges  them  into  the  line  of 
tile  from  which  the  liquids  leach  out  through  joints  into  the  soil.  In  a 
tank  constructed  as  shown  in  the  design  mentioned,  it  is  very  important 
to  use  a  siphon  to  empty  the  second  compartment  at  intervals  instead 
of  allowing  a  continuous  outward  flow  of  contents,  because  of  the  tend- 
ency for  drains  to  become  clogged  when  liquids  are  constantly  trickling 
through. 

"The  size  of  tank  required  for  residence  use  depends  upon  the  quan- 
tity of  sewage  to  be  handled  in  the  first  chamber  during  a  day  of  24 
hours;  therefore,  this  compartment  should  be  large  enough  to  contain 
an  entire  day's  flow.  This  frequently  amounts  to  from  30  to  50  gallons 
per  person  per  day,  so  the  required  capacity  can  readily  be  computed 
from  these  figures,  although  it  must  be  remembered  that  the  required 
depth  for  the  tank  should  be  figured  from  the  top  of  the  concrete  baffle 
wall  or  partition  which  separates  the  first  and  second  compartments. 
Another  point  to  bear  in  mind  is  that  the  width  of  the  first  compartment 
hould  be  about  one-half  its  length." 


CHAPTER  IX 
COAL 

Coal  is  of  prehistoric  origin,  formed  from  accumulation  of 
vegetable  matter,  supposed  to  be  the  remains  of  immense  forests. 
In  past  ages  the  deposits  underwent  destructive  distillation  from 
great  heat  and  was  subjected  to  pressure,  sufficient  to  compress  it 
into  varying  degrees  of  hardness.  Coal  is  composed  of  carbon, 
hydrogen  and  oxygen,  with  small  quantities  of  nitrogen  and  vary- 
ing amounts  of  sulphur  and  ash. 

The  coals  from  different  geological  formations  vary  in  quality 
from  the  hard  dry  anthracites  to  the  soft  wet  lignites,  with  the 
intermediate  bituminous  coals;  all  of  which  furnish  fuels  that  when 
burned  will  produce  amounts  of  heat,  depending  on  their  com- 
position, the  quantity  of  moisture  contained  and  the  conditions 
of  their  combustion. 

Carbon,  of  which  coal  is  principally  composed,  exists  in  differ- 
ent combinations,  depending  on  the  condition  of  its  formation. 
Part  of  the  carbon  is  combined  with  hydrogen  to  form  hydro- 
carbon that  may  be  driven  off  when  heated,  and  which  forms  the 
volatile  portion  of  the  coal.  The  remainder  of  the  carbon  appears 
in  the  form  of  coke — when  the  volatile  matter  is  driven  off — and 
is  said  to  be  fixed.  The  fixed  carbon  and  volatile  constituents 
together  make  up  the  combustible. 

Other  ingredients  of  coal  that  require  attention  are  the  mois- 
ture, and  the  incombustible  matter  that  forms  ash.  Moisture 
varies  in  quantity  from  as  low  as  0.75  per  cent,  in  hard  coal  to  50 
per  cent,  in  lignite.  The  amounts  of  ash  in  different  coals  vary 
from  3  to  30  per  cent,  of  the  weights  of  the  fuel . 

The  heating  value  of  coals  differs  in  amount  by  reason  of  the 
variable  quantities  of  fixed  and  combined  carbons,  moisture  and 
ash.  Different  coals  are  compared  in  value  by  the  number  of 
B.t.u.  per  pound  of  dry  coal  that  can  possibly  be  developed  when 
burned,  and  with  these  factors  are  given  the  percentages  of 
moisture  and  ash. 

There  are  no  distinct  demarkations  between  different  grades  of 

182 


•is- 


COAL  183 

coal.  The  classifications  are  made  because  of  their  chief  charac- 
teristics and  they  commonly  are  graded  as  anthracites,  semi- 
anthracites,  semi-bituminous  and  bituminous  coals.  These 
classes  comprehend  the  most  common  commercial  coals  of  the 
United  States.  Aside  from  those  named  are  forms  of  coal  that 
are  occasionally  found,  such  as  graphitic  anthracite,  cannel  coal, 
etc.,  and  the  various  lignites. 

The  value  of  coal  as  a  heat-producing  agent  is  represented  by 
the  B.t.u.  it  is  capable  of  turning  to  useful  account.  The  price 
of  coal  should  be  based  on  the  amount  of  heat  it  is  capable  of 
generating  when  burned.  In  considering  the  value  of  coal  for 
any  particular  purpose,  thought  must  be  taken  as  to  its  charac- 
teristic properties,  for  coals  that  produce  excellent  results  for  one 
purpose  may  be  very  unsatisfactory  in  others.  Soft  coal  con- 
taining a  large  percentage  of  volatile  matter  usually  produces  a 
great  amount  of  smoke  and  unless  carefully  fired  this  will  con- 
dense and  form  accumulations  of  soot  that  are  objectionable. 
For  reasons  of  this  kind  bituminous  coals  are  often  sold  at  a  lower 
price  than  their  rated  heating  value  might  indicate. 

Anthracite  or  hard  coal  possesses  bright  lustrous  surfaces  when 
newly  fractured,  that  when  handled  do  not  soil  the  hands.  It  con- 
tains a  high  percentage  of  carbon,  a  small  amount  of  volatile 
matter  and  little  moisture.  It  is  greatly  in  demand  as  a  domestic 
fuel  because  it  burns  slowly  with  an  intense  heat,  practically 
without  flame  and  produces  no  smoke.  It  invariably  commands 
a  higher  price  than  soft  coal,  but  in  heating  value  is  not  superior 
to  the  better  grades  of  soft  coal.  In  furnaces  for  house  heating 
the  use  of  soft  coal  often  gives  better  satisfaction  than  hard  coal. 

The  grades  of  hard  coal  found  in  the  market  will  vary  with  the 
demand  in  any  locality  but  those  recognized  by  the  trade  are: 

Egg Coal  will  pass  through  2%-inch  mesh  screen. 

Stove Coal  will  pass  through  2-inch  mesh  screen. 

Chestnut Coal  will  pass  through  1%-inch  mesh  screen. 

Pea Coal  will  pass  through  %-inch  mesh  screen. 

No.  1  Buckwheat  Coal  will  pass  through  K-mch  mesh  screen. 

No.  2  Buckwheat  Coal  will  pass  through  ^-inch  mesh  screen. 

No.  3  Buckwheat  Coal  will  pass  through  ^-inch  mesh,  screen. 

Hard  coal  of  stove  and  chestnut  sizes  are  those  most  commonly 
used  for  domestic  heating,  because  they  are  well  suited  for 


184  MECHANICS  OF  THE  HOUSEHOLD 

furnaces  and  heating  stoves.  Of  the  two  sizes  chestnut  coal  is 
most  largely  used  and  on  account  of  the  greater  demand,  the 
price  for  this  size  is  usually  somewhat  in  advance  of  the  others ;  at 
the  same  time  the  smaller  sizes — pea  and  buckwheat  coals' — are 
less  in  price  for  the  same  grade  of  coal.  Under  conditions  that  will 
permit  their  use  the  latter  coals  are  an  economical  form  of  fuel. 

Bituminous  or  soft  coal  represents  the  chief  fuel  of  commerce. 
The  market  prices  of  these  coals  are  determined  largely  by  reason 
of  their  reputation  as  desirable  fuel.  The  variations  in  price 
depend  on  the  physical  qualities,  rather  than  on  the  amount  of  heat 
evolved  in  combustion.  The  compositions  of  coals  vary  markedly 
in  different  localities  and  often  in  the  same  locality  several  grades 
are  produced.  It  sometimes  happens  that  from  different  parts 
of  a  mine  the  coal  will  differ  very  much  in  heat  value. 

Bituminous  coals  are  roughly  classified  as  coking  and  free- 
burning.  The  former  is  valuable  for  gas  manufacture  and  for 
production  of  coke.  The  coking  coals  fuse  on  being  heated, 
allowing  the  volatile  portion  to  escape;  and  when  the  gas  has 
been  all  distilled,  the  residue  is  coke.  When  used  for  gas  making, 
the  volatile  portion  forms  the  illuminating  gas.  When  burned 
in  a  furnace,  the  gases  from  soft  coal  burn  with  a  yellow  flame  and 
usually  with  considerable  smoke.  The  classification  of  bitumi- 
nous coals  differ  somewhat  in  the  East  from  that  of  the  West. 
Eastern  bituminous  coals  are  commonly  graded: 

%;  Run-of-mine  coal  =  unscreened  coal  as  taken  from  the  mine. 

^B.  Lump  coal  =  that  which  passes  over  a  bar  screen  with  1 
openings. 

>-C.  Nut  coal  =  that  which  passes  through  a  bar  screen  with  1 
Openings  and  over  one  with  %-inch  openings. 

D.  Slack  =  all  that  which  passes  through  a  %-inch.  bar  screen. 

Western  bituminous  coal: 

E.  Run-of-mine  coal  =  the  unscreened  coal  as  taken  from  the  mine. 

F.  Lump  coal — divides  as  6-inch,  3-inch  and  Ij^-inch  according  to  the 
diameter  of  the  mesh  through  which  the  pieces  pass  the  screens. 

G.  Nut  coal — varying  from  1 34-inch  size  to  %-inch  in  diameter. 

H.  Screening  =  all  coal  which  passes  a  134 -inch  screen  including  the 
dust. 

Heat  derived  from  coal — or  any  other  fuel — in  the  process 
of  combustion  is  due  to  oxidation.  Combustion  or  burning 
is  caused  by  rapid  oxidation.  When  oxygen  combines  with 


COAL  185 

carbon  in  sufficient  quantities,  carbon  dioxide  is  formed  and  at 
the  same  time  heat  is  liberated.  In  burning  fuel,  if  the  carbon 
is  completely  oxidized  and  changed  into  carbon  dioxide,  the  great- 
est amount  of  heat  is  produced.  The  required  oxygen  is  fur- 
nished by  the  air,  which  through  the  dampers  of  the  furnace 
regulates  the  rate  of  combustion. 

Oxidation  of  Hydrocarbons. — In  the  oxidation  of  hydrocarbons, 
as  that  of  burning  coal  gas,  the  combination  o^the  elements  forms 
carbon  dioxide  and  water.  The  presence  of  the  water,  formed 
in  combustion,  is  often  shown  in  the  formation  of  moisture  on 
the  bottom  of  a  cold  vessel  when  placed  over  a  gas  flame.  The 
same  effect  is  observed  in  a  newly  lighted  kerosene  lamp,  when 
the  film  of  moisture  forms  inside  the  cold  lanip  chimney.  As  soon 
as  the  surfaces  become  heated  the  moisture  is  evaporated.  Oc- 
casionally, the  accumulation  of  moisture  in  chimneys,  from  this 
cause,  is  sufficient  during  extremely  cold  weather  to  form  ice 
in  the  part  of  the  chimney  exposed  to  the  outside  air.  Chimneys 
have  been  known  to  become  so  stopped  by  accumulation  of  ice 
from  this  cause  as  to  materially  interfere  with  the  draft. 

The  fixed  carbon  of  the  coal,  when  oxidized,  has  a  constant 
heating  value  of  14,000  B.t.u.  per  pound.  The  volatile  hydro- 
carbons develop  amounts  of  heat  when  burned,  depending  on 
their  composition,  and  differ  in  coals  from  different  localities. 
The  heat  obtained  from  the  volatile  part  of  coal  depends  on  its 
chemical  composition  and  differs  very  materially;  it  may  be  as 
high  as  21,000  B.t.u.  per  pound,  or  as  low  as  12,000  B.t.u.  per 
pound. 

A  high  percentage  of  volatile  matter  usually  indicates  a  fuel 
that  will  produce  a  large  volume  of  smoke,  which— unless  the 
combustion  is  complete  in  the  furnace — will  deposit  soot  as 
soon  as  it  is  condensed,  either  in  the  chimney  or  in  the  outside 
air.  The  ash  has  no  heating  value,  and  the  contained  moisture 
has  a  negative  heating  effect,  because  considerable  heat  is  re- 
quired to  evaporate  and  raise  it  to  the  temperature  of  the  gases 
of  the  furnace.  In  burning  fuel  the  moisture  uses  up  the  heat 
of  combustion  in  proportion  as  it  appears  in  the  coal.  The 
moisture  is  bought  as  coal  but  requires  heat  to  get  rid  of  it;  so  the 
percentage  of  water  in  coal  should  be  considered  very  carefully. 

It  is  customary  in  comparing  the  heating  values  of  coals,  to 


186  MECHANICS  OF  THE  HOUSEHOLD 

state  the  proportionate  parts  of  fixed  carbon,  volatile  matter, 
moisture  and  ash  as  well  as  the  B.t.u.  per  pound  of  dry  coal.  The 
heat  value  in  B.t.u.  per  pound  of  fuel  is  usually  obtained  by  burn- 
ing samples  in  a  calorimeter  from  which  the  heat  per  pound  is 
calculated.  The  heat  value  of  fuels  used  in  power  plants  are 
often  determined  by  careful  tests  of  the  amount  of  power  derived 
for  each  pound  of  fuel  burned  in  the  furnace.  This  is  done  by 
weighing  the  fuel  burned  and  measuring  the  water  evaporated. 
The  ashes  are  weighed  and  this  weight  together  with  the  weight 
of  moisture  present  is  subtracted  from  that  of  the  coal  to  de- 
termine the  amount  of  combustible  of  the  fuel.  The  final  results 
are  expressed  by  the  number  of  pounds  of  water  evaporated  per 
pound  of  combustible  and  also  the  weight  to  water  evaporated 
per  pound  of  coal  burned. 

Semi-bituminous  coal  represents  a  class  between  the  hard  and 
soft  grades.  It  contains  less  carbon  and  more  volatile  matter 
than  hard  coal.  It  burns  with  a  short  flame  with  very  little 
smoke  and  is  valuable  as  a  furnace  fuel.  The  Pocahontas  coal 
of  West  Virginia  is  an  example  of  this  class.  Semi-bituminous 
coal  is  often  called  smokeless  coal,  because  in  burning  it  produces 
relatively  little  smoke.  It  will  be  noted  in  the  table  of  heat 
values  on  page  192  that  coal  of  this  variety  has  high  heat-pro- 
ducing properties.  It  is  a  very  friable  coal  and  for  that  reason  is 
apt  to  contain  considerable  dust.  As  a  furnace  fuel  it  produces — 
when  carefully  fired — very  satisfactory  results. 

Graphitic  Anthracite. — This  is  a  type  of  coal  found  in  Rhode 
Island  and  Massachusetts  which  resembles  both  graphite  and 
anthracite  coal.  It  is  gray  in  color,  very  hard  and  burns  with 
extreme  difficulty. 

Cannel  Coal. — This  is  a  variety  of  bituminous  coal,  rich  in 
hydrocarbons.  It  burns  with  a  bright  flame  without  fusing  and 
is  often  used  for  open  fires. 

Lignite. — This  is  a  type  of  fuel  that  in  point  of  geological  for- 
mation represents  the  condition  between  true  coal  and  peat. 
Lignite  occurs  in  immense  deposits  throughout  the  middle 
portion  of  the  western  half  of  the  United  States,  where  beds  20 
feet  in  depth  are  not  uncommon.  It  varies  in  color  from  black 
to  brown  and  in  many  localities  is  known  as  brown  coal. 

When  newly  mined,  lignite  contains  a  large  percentage  of 
water,  sometimes  as  high  as  50  per  cent.  On  account  of  this 


COAL  187 

large  moisture  content  it  has  a  relatively  low  calorific  value, 
but  when  dry  the  amount  of  heat  evolved  per  pound  compares 
very  favorably  with  soft  coal. 

Peat. — As  a  fuel,  peat  has  been  used  very  little  in  the  United 
States  on  account  of  the  abundance  of  the  better  grades  of  fuel, 
but  in  many  parts  of  the  country  it  is  used  locally  to  a  consider- 
able extent.  In  peat  bogs  from  which  the  fuel  is  taken,  the  peat 
is  formed  from  grasses  and  sedges  which  in  time  produce  a  car- 
bonaceous mass  that  becomes  sufficiently  dense  to  be  taken  out  in 
sections,  with  a  long  narrow  spade.  The  peat  is  then  built  into 
piles  where  after  drying  it  is  ready  to  be  burned. 

Wood. — On  account  of  its  relative  scarcity  and  correspond- 
ingly high  price,  wood  is  no  longer  a  commercial  fuel  of  any  con- 
sequence. The  low  heating  value  of  wood  as  compared  with  coal 
makes  it  a  prohibitive  fuel  except  in  forest  localities.  Wood  is 
commonly  sold  by  the  cord  and  no  attention  is  given  by  dealers 
to  its  value  in  heat-producing  capacity. 

The  desirability  of  wood  as  a  fuel  is  chiefly  that  of  reputation. 
It  is  usually  considered  that  hickory  is  the  ideal  fire  wood,  dry 
maple  a  close  second  and  that  oak  is  next  in  desirability  as  fuel; 
following  which  are  ash,  elm,  beech,  etc.,  depending  on  the  den- 
sity of  the  wood.  The  price  of  wood  per  cord  depends  on  the 
nearness  and  abundance  of  supply. 

The  actual  heating  values  of  different  woods  as  determined  by 
Gottlieb  show  that  per  pound  of  dry  wood  there  is  little  difference 
in  heat  value  between  different  kinds  of  hard  woods,  and  that 
pine  gives  per  pound  the  highest  value  of  all.  The  table  given 
below  was  taken  from  "Steam"  published  by  the  Babcock- 
Wilcox  Co. 

Per  cent,  of  B.t.u.  per 

Kinds  of  wood  ash  pound 

Oak 0.37  8,316 

Ash 0.57  8,480 

Elm 0.50  8,510 

Beech 0.57  8,591 

Birch 0.29  8,586 

Fir 0.28  9,063 

Pine 0.37  9,153 

Poplar 1.86  7,834 

Willow..  .3.37  7,926 


188  MECHANICS  OF  THE  HOUSEHOLD 

In  considering  this  table  it  must  be  kept  in  mind  that  the 
values  are  for  dry  wood  per  pound. 

As  given  in  Kent's  " Engineer's  Pocket  Book"  the  weights  of 
different  fuel  woods  per  cord  (thoroughly  air-dried)  are  about 
as  follows: 

1  cord  hickory  or  hard  maple. .   4,500  pounds  equal  to  1,800  pounds  coal 

1  cord  white  oak 3,850  pounds  equal  to  1,540  pounds  coal 

1  cord  beech,  red  and  black  oak  3,250  pounds  equal  to  1,300  pounds  coal 
1  cord  poplar,  chestnut  and  elm  2,350  pounds  equal  to  940  pounds  coal 
1  cord  average  pine 2,000  pounds  equal  to  800  pounds  coal 

The  above  values  in  pounds  of  coal  may  be  taken  to  represent 
average  bituminous  coals.  As  given  by  Suplees  ''Mechanical 
Engineers'  Reference  Book,"  eight  samples  of  coals  representing 
bituminous  coals  from  mines  east  of  the  Mississippi  River  give 
an  average  heating  value  of  13,755  B.t.u.  per  pound. 

Charcoal. — This  is  made  from  wood  by  driving  off  the  volatile 
constituents;  the  residual  carbon,  which  forms  the  charcoal  is  a 
fuel  that  burns  without  smoke  or  flame.  Charcoal  is  made  by 
piling  wood  in  a  heap,  which  is  covered  with  earth.  In  the  bot- 
tom of  the  heap  a  fire  generates  the  necessary  heat  for  distilling 
off  the  volatile  matter.  Charcoal  holds  to  wood  the  same  re- 
lation that  coke  bears  to  coal. 

Coke. — This  is  the  residue  from  the  distillation  of  coal.  It 
comprises  from  60  to  70  per  cent,  of  the  original  coal  and  contains 
most  of  the  carbon  and  all  of  the  ash  of  the  coal.  Coke  is  gray  in 
color  and  has  a  slightly  metallic  luster;  it  is  porous,  brittle  and  in 
handling  gives  out  something  of  a  metallic  ring.  It  is  often  sold 
for  fuel  as  a  byproduct  by  gas  factories.  In  heating  value  gas- 
coke  gives  about  14,000  B.t.u.  per  pound  when  dry  and  as  a  con- 
sequence is  rated  as  an  excellent  fuel.  Clean  coke  burns  without 
flame  and  is  capable  of  producing  an  intense  heat.  On  account 
of  its  porous  nature  it  occupies  a  relatively  large  volume  per  ton. 
It  is  most  successfully  burned  in  stoves  and  furnaces  with  large 
fire-boxes. 

Gas-coke,  which  is  the  residue  from  the  gas  retorts,  is  some- 
what inferior  in  heating  value  to  coke  made  in  ovens  but  it  is 
an  excellent  fuel  where  furnaces  are  adapted  to  its  use.  Gas-coke 
is  often  stored,  by  piling  it  in  heaps,  in  the  open  and  on  account 


COAL  189 

of  its  porous  nature  it  absorbs  considerable  moisture.  Where 
exposed  to  the  weather  the  amount  of  contained  moisture  de- 
pends on  the  amount  of  rain  or  snow  the  coke  has  absorbed.  This 
amount  is  easily  determined  by  weighing  a  fair  sample  and  driv- 
ing off  the  moisture  in  an  oven.  The  sample  should  be  weighed 
several  times  until  the  weight  remains  constant. 

Briquettes. — Briquetted  coal  and  other  fuels  are  produced 
by  compressing  coal  dust  or  other  powdered  fuel,  mixed  with  coal 
tars  or  other  bituminous  binder  in  sufficient  quantity  to  cause 
the  adhesion  of  the  particles  when  pressed  into  form  under  great 
pressure.  Owing  to  the  relative  cheapness  of  fuel,  briquettes 
have  been  used  but  very  little  in  the  United  States.  With  the 
advance  in  the  price  of  coal  of  the  past  few  years,  they  have 
found  a  place  on  the  market  ancj  have  become  a  common  form 
of  fuel. 

The  heat  value  of  briquettes  will  depend  on  the  kind  and 
quality  of  material  that  enters  into  their  composition.  Quite 
generally,  they  produce  heat  equal  to  the  average  grade  of  soft 
coal.  In  the  Northwest  briquettes  made  of  West  Virginia 
semi-bituminous  coal  sell  at  the  same  price  as  run-of-mine 
coal  of  the  same  quality.  Their  use  has  proven  satisfactory 
as  a  furnace  fuel  and  they  will  very  likely  be  sold  in  increasing 
quantities. 

Comparative  Value  of  Coal  to  Other  Fuels. — Until  a  compara- 
tively recent  time,  coal  has  been  sold  by  weight  and  reputation 
alone;  but  conditions  are  rapidly  approaching,  which  will  require 
it  to  be  sold  according  to  its  composition  and  heating  value. 
Among  manufacturers  and  others  using  large  quantities  of  fuel, 
the  practice  of  contracting  for  coal  by  specificatiqn  isHbecomihg 
increasingly  common.  The  determining  factors  are  the  amounts 
of  moisture,  ash,  sulphur,  carbon,  and  volatile  matter  the  coal 
contains,  as  well  as  the  size  of  the  pieces  and  freedom  from  dust. 
In  a  few  of  the  most  progressive  cities,  coal  dealers  are  required 
to  supply  coal  for  schools  and  other  municipal  uses,  which 'has 
been  subject  to  the  approval  of  the  City  Engineer.  The  time  is 
not  far  distant  when  dealers  will  be  required  to  submit  samples 
of  all  fuel,  for  sale  to  the  public,  to  the  examination  of  t{ie  munici- 
pal authorities. 


190  MECHANICS  OF  THE  HOUSEHOLD 

The  following  table  of  the  heating  values  of  various  fuels  is 
taken  from  Benson's  " Industrial  Chemistry." 


BRITISH  THERMAL  UNITS  FOR  ONE  CENT  FROM  DIFFERENT  FUELS 

Acetylene,  from  carbide  at  10  cents  per  pound 600 

Denatured  alcohol,  at  40  cents  per  gallon 2,000 

Air  gas  (from  gasoline,  80°Be  at  25  cents  per  gallon) .     3,000 

Water  gas,  at  $1  per  1000  cubic  feet 3,000 

Coal  gas,  at  $1  per  1000  cubic  feet. 6,500 

Gasoline,  at  20  cents  per  gallon 7,500 

Kerosene,  at  15  cents  per  gallon 11,000 

Natural  gas,  at  50  cents  per  1000  cubic  feet 18,000 

Charcoal,  at  10  cents  per  bushel  (15  pounds) 20,000 

Petroleum  at  5  cents  per  gallon 30,000 

Producer  gas,  from  anthracite,  $7  per  ton 30,000 

Producer  gas,  from  coke,  $5  per  ton 36,000 

Anthracite,  at  $7  per  ton 46,000 

Producer  gas,  from  soft  coal,  at  $3  per  ton 50,000 

Coke,  at  $5  per  ton 54,000 

Mond  producer  gas  from  soft  coal,  at  $3  per  ton 65,000 

Soft  coal,  at  $3  per  ton 80,000 


Price  of  Coal. — The  value  of  coal  as  a  fuel  will  depend  on  the 
amount  of  heat  it  is  capable  of  producing  when  burned;  its  price 
should  therefore  be  determined  by  the  heating  value  per  pound 
of  fuel  as  purchased.  Secondary  determining  factors  in  price  are 
those  of  convenience  of  handling  and  the  difficulty  in  burning  the 
fuel  such  as  the  size  and  uniformity  of  the  pieces,  the  formation 
of  clinkers,  smoke  and  accumulation  of  soot.  Soft  coals,  contain- 
ing a  large  amount  of  volatile  matter,  usually  produce  much  soot 
and  smoke  and  as  a  consequence  sell  for  a  lower  price  than  coals 
that  produce  little  smoke. 

The  selection  of  fuels  will  depend  on  the  type  of  heating  plant 
in  use,  whether  by  stoves  or  by  furnaces.  If  by  stoves,  whether  it 
is  possible  to  use  soft  coal  as  a  fuel.  The  automatically  fed 
stove,  of  the  base-burner  type,  are  usually  designed  for  the  use  of 
hard  coal  and  in  such  stoves  the  use  of  soft  coal  would  not  be 
possible.  Other  stoves  and  furnaces  are  usually  capable  of  burn- 
ing soft  coal  with  varying  degrees  of  satisfaction,  depending  on 
the  design  and  surrounding  conditions. 


COAL  191 

The  following  prices,  from  the  local  market,  show  the  usual 
ratings  of  various  fuels  in  common  use.  These  prices  vary  with 
the  locality  and  somewhat  with  the  season.  It  is  usually  possible 
to  purchase  coal  at  some  reduction  in  price  during  the  summer 
months  when  the  demand  for  coal  is  light. 


Hard  coal — stove  size $10 . 25  per  ton 

Hard  coal — nut  size 10 . 50  per  ton 

Semi-bituminous — run-of-the-mine 9.00  per  ton 

Pennsylvania  bituminous — run-pf-the-mine 7 . 50  per  ton 

Soft  coal — Ohio — run-of-the-mine 7 . 50  per  ton 

Soft  coal — Illinois — bituminous — run-of-the-mine 7 . 50  per  ton 

Soft  coal — Iowa — bituminous — run-of-the-mine 7 . 50  per  ton 

Briquettes-mixture  semi-bituminous  coal  dust 9.00  per  ton 

Wood  (oak),  sawed,  stove  length  and  split 8.50  per  cord 


The  price  of  coal  is  determined  in  many  localities  by  the  dis- 
tance from  the  sources  of  supply  and  the  means  of  transportation. 
The  fact  that  coals  from  all  of  the  principal  mining  areas  from 
Pennsylvania,  west  to  Iowa,  are  sold  at  points  in  the  Northwest 
for  the  same  price,  is  due  in  greatest  measure  to  transportation 
rates  on  the  Great  Lakes.  The  prices  of  Eastern  coals  at  Duluth 
are  such  that  in  competition  with  Western  coals  they  are  sold  at 
the  same  price  as  is  shown  by  the  table. 

It  is  usually  impossible  for  the  average  householder,  or  even 
the  dealer,  to  determine  definitely  the  exact  locality  from  which 
his  fuel  is  mined.  Even  when  such  information  is  obtainable, 
the  quality  is  still  in  doubt,  unless  analysis  is  obtainable  by  sample. 
The  data  given  in  the  following  tables  is  such  as  will  furnish  a  fair 
knowledge  of  the  relative  heating  values  of  coals  from  the  prin- 
cipal mining  areas  of  the  United  States.  The  data  was  obtained 
from  a  considerable  number  of  authorities  but  chiefly  from  the 
reports  of  the  United  States  Geological  Survey.  The  different 
items  are  not  intended  to  be  exact,  they  merely  represent  reliable 
average  conditions. 

>  The  varying  conditions  of  available  heat  and  percentage  of 
moisture  given  in  the  following  table  are  such  as  to  be  of  little 
use  to  those  unaccustomed  to  problems  of  this  kind,  unless  a 
systematic  method  of  comparison  is  made  of  the  different  fuels. 


192 


MECHANICS  OF  THE  HOUSEHOLD 


APPROXIMATE  COMPOSITION  AND  CALORIFIC  VALUE  OF  TYPICAL  AMERICAN  COALS 


1 
Local- 
ity 

2 
Kind  of  coal 

3 

Number, 
of  samples 
examined 

Moisture 

5 
Volatile 
matter 

6 
Fixed 
carbon 

7 
B.t.u.  per 
pound 
dry  coal 

8 

Ash 

Pa... 

Anthracite 

12 

5.05 

5.52 

82.54 

12,682 

11.53 

Md.. 

Semi- 

5 

2.39 

17.73 

75.44 

14,530 

7.40 

bituminous 

Pa.  .'. 

Semi- 

15 

3.60 

19.26 

74.46 

14,211 

8.32 

bituminous 

W.Va 

Semi- 

12 

2.50 

19.00 

75.70 

14,758 

5.24 

Bituminous 

Ala.. 

Bituminous 

6 

3.55 

29.99 

59.24 

13,522 

10.73 

Ark.. 

Bituminous 

2 

1.42 

16.58 

73.37 

14,205 

10.05 

Colo.. 

Bituminous 

6 

9.89 

37.34 

52.53 

12,325 

10.32 

111.... 

Bituminous 

22 

10.31 

36.73 

50.52 

11,504 

12.73 

la.... 

Bituminous 

8 

7.72       39.15 

50.54 

12,656 

10.33 

Kan.. 

Bituminous 

3 

4.25 

32.20 

51.17 

12,031 

13.75 

Ky... 

Bituminous 

9 

5.99 

34.58 

56.56 

13,341 

8.86 

Mo... 

Bituminous 

9 

11.52 

37.85 

48.11 

12,398 

14.04 

Ohio. 

Bituminous 

14 

5.65 

38.51 

50.59 

12,839 

10.65 

Okla. 

Bituminous 

3 

5.72 

34.83 

52.76 

12,648 

12.41 

NM.. 

Bituminous 

1 

12.17 

36.31 

51.17 

12,126 

12.52 

Pa.  .. 

Bituminous 

15 

2.44 

33.41 

58.31 

13,732 

8.40 

Tenn. 

Bituminous 

4 

2.53 

36.58 

58.21 

14,098 

5.47 

Tex.. 

Bituminous 

3 

3.84 

35.05 

48.99 

12,302 

15.96 

Va... 

Bituminous 

5 

2.71 

31.32 

62.47 

14,025 

6.92 

W.Va 

Bituminous 

10 

2.61 

33.92 

58.80 

14,094 

7.27 

Colo.. 

Lignite 

6 

19.75       45.21 

45.85 

10,799 

8.93 

N.  D. 

Lignite 

5 

35.93  ||    44.33 

43.21 

10,420 

12.45 

Tex.. 

Lignite 

6 

30.86 

44.06 

39.21 

10,297 

16.76 

Wyo. 

Lignite 

4 

14.71 

48.47 

44.49 

11,608 

7.035 

The  following  table  was  prepared  from  the  date  of  that  preceding 
combined  with  the  prices  of  various  coals  to  be  obtained  in  the 
local  market.  The  table  is  intended  to  present  a  method  of 
comparing  the  values  of  fuels  from  different  coal  areas.  The 
consumer  is  interested  to  know  the  amount  of  heat  purchased  in 
the  form  of  fuel.  The  table  shows  in  the  column  headed  "Heat 
per  $1,"  the  number  of  B.t.u.  purchased  for  $]  in  coal;  the  number 
of  available  B.t.u.  in  the  different  kinds  of  coal  may  be  taken  as  a 
relative  comparison  of  their  values  as  fuel. 

The  gas-coke  in  the  table  is  that  sold  by  the  local  gas  company. 
The  amount  of  moisture  in  this  case  is  relatively  high  because  of 


COAL 


193 


the  fact  that  the  coke  is  stored  in  a  yard  exposed  to  the  weather, 
where  it  absorbs  all  precipitated  moisture.  A  less  amount  of 
moisture  would  give  a  higher  value  for  the  same  fuel. 


B.t.u.  to 

B.t.u.  per 

Kind  of  coal 

Price 
per 

Per 

cent.. 

B.t.u.  per 
100  pounds 

evaporate 
water 

100  -^  cost 
per  100 

Heat  per  $1 

ton 

water 

pounds 

Bituminous  $?  5Q       2  44          1>340,000   -     3,439   =l~~~    =     3,564,000  B.t.u. 
Pennsylvania  $0  •  o«  5 

Semi-  1  415  685 

bituminous  $9.00       3.06         1,420,000   -  4,315     =      '  Q  ^       =   3,145,000    B.t.u. 

West  Virginia 

Gas-coke  $7.00     10.00         1,117,900  -  16,888  =  1'^1>3°512   =   3,145,000  B.t.u. 


North 
Dakota 
lignite 

$4.50 

35.90 

668,000 

607,282 

=   2,703,000  B.t.u. 

$0.225 

Bituminous 
Illinois 

$7.50 

10.31 

1,032,000  • 

-  14,398     = 

1,017,602 

=   2,980,000  B.t.u. 

$0.375 

Bituminous 
Iowa 

$7.50 

13  .  10 

1,012,000 

-  18,471    = 

994,529 
$0.375 

=    2,652,000  B.t.u. 

Hard  coal 
Pennsylvania 

$10.50 

3.05 

1,230,000 

-    4,195   = 

1,225,905 

=    2,335,000  B.t.u. 

$0.525 

Semi-bituminous  coal  commands  considerable  favor  as  a 
house-heating  fuel,  because  of  the  fact  that  it  burns  with  much 
less  smoke  than  bituminous  coal.  In  available  heat  it  is  con- 
siderably above  the  Western  bituminous  coal  and  it  sells  at  a 
price  $1.50  higher  per  ton.  The  reason  for  the  difference  in 
price  is  not  so  much  on  account  of  its  heating  value,  as  because 
of  relatively  small  amount  of  smoke  produced  in  combustion. 
Other  coals  capable  of  producing  more  heat  are  sold  at  less  price 
because  of  smoke  and  soot  produced  in  burning. 

Hard  coal  at  $10.50  is  the  most  expensive  coal  of  all.  The 
ratio  of  available  heat  units  per  $1  for  hard  coal,  as  compared 
with  the  best  soft  coal,  is  as  23  is  to  35.  This  means  that  at  the 
stated  prices  those  who  burn  hard  coal  pay  the  additional  price, 
because  of  the  physical  properties  it  possesses. 

In  constructing  the  above  table,  100  pounds  of  coal  was  taken 
as  a  unit  of  comparison.  The  price  per  ton  is  that  given  in  the 
table  of  local  prices.  The  per  cent,  of  moisture  and  the  B.t.u. 
per  pound  of  fuel  was  taken  from  table  on  page  192. 

13 


194  MECHANICS  OF  THE  HOUSEHOLD 

In  explaining  the  method  by  which  the  different  items  were 
obtained,  it  will  be  necessary  to  discuss  briefly  the  condition  of 
combustion  and  the  heat  losses  that  take  place  when  fuel  is 
burned. 

The  moisture  in  the  fuel  is  the  undesirable  part,  because  it 
requires  a  large  amount  of  heat  to  dispose  of  it.  It  is  looked  upon 
as  so  much  water,  that  must  be  raised  in  temperature  from  that 
in  which  it  is  taken  from  the  coal  bin  to  the  temperature  and  con- 
dition of  vapor  in  which  it  passes  into  the  chimney.  When  the 
fuel  enters  the  furnace  the  water  is  heated  to  the  boiling  point. 
In  changing  temperature  it  absorbs  i  B.t.u.  for  each  pound  of 
water,  through  each  degree  of  change.  Suppose  that,  as  in 
the  case  of  Pennsylvania  bituminous  coal  which  contains  2.44 
pounds  of  water  to  each  100  pounds  of  coal,  the  coal  entering 
the  furnace  was  at  50°F.  To  raise  its  temperature  to  the  boiling 
point  (212°F.)  required  a  change  of  162*.  The  2.44  pounds  of 
water  raised  this  amount 

162  X  2^4  =  395.28  B.t.u. 

To  change  the  2.44  pounds  of  water,  into  steam  at  the  atmos- 
pheric pressure  requires  969..  7  B.t.u.  (heat  of  vaporization), 
practically  970  B.t.u.  per  pound  of  water.  The  heat  required 
to  vaporize  2.44  pounds  of  water  is 

2.44  X  970  =  2366.80  B.t.u. 

The  vapor  is  now  raised  in  temperature,  to  that  of  the  furnace, 
which  we  may  assume  is  1200°F.  The  furnace  being  at  atmos- 
pheric pressure  the  vapor  merely  expands  in  volume  as  a  gas. 
The  specific  heat  of  steam  at  atmospheric  pressure  is  0.464; 
that  is,  1  pound  of  steam  requires  only  0.464  B.t.u.  to  raise  it  a 
degree,  and  2.44  pounds  of  water  will  absorb 

0.464  X  2.44  X  1200  =  1356.00  B.t.u. 

Of  this  last  amount  of  heat,  approximately  50  per  cent,  is 
recovered  as  the  gases  pass  through  the  furnace.  The  total 
loss  of  heat  due  to  the  evaporation  of  the  water  is 

Raising  temperature  from  normal  to  212° 395  B.t.u. 

Evaporation 2,366  B.t.u. 

Changing  temperature  of  vapor,  less  50  per  cent.      678  B.t.u. 

Total  heat  loss. .  3,439  B.t.u. 


COAL  195 

In  the  100  pounds  of  coal  under  consideration,  there  is  100 
pounds,  less  2.44  pounds  of  water,  or  97.56  of  dry  coal,  each 
pound  of  which  contains  13,732  B.t.u.  as  given  by  the  table  on 
page  193.  This  gives 

97.56  X  12,682  =  1,339,753  =  practically  1,340,000  B.t.u. 
From  this  quantity  is  subtracted  the  loss  of  heat,  3439. 
1,340,000  -  3439  =  1,336,561  B.t.u. 

This  represents  the  total  available  heat  in  100  pounds  of 
coal.  If  this  quantity  is  now  divided  by  the  cost  of  100  pounds 
of  coal  at  $7.25  per  ton,  the  result,  3,564,000  B.t.u.,  will  be  the 
available  heat  bought  for  $1  as  given  in  column  7  of  the  table. 


CHAPTER  X 
ATMOSPHERIC  HUMIDITY 

The  physical  effect  of  atmospheric  humidity  has  come  to  be 
recognized  by  all  who  deal  in  problems  of  house  heating,  sani- 
tation and  hygiene.  The  difference  in  effect  of  dry  atmosphere, 
from  that  of  air  containing  a  desirable  degree  of  moisture,  is 
very  noticeable  in  all  buildings  that  are  artificially  heated.  The 
effect  of  dry  air  is  made  apparent  in  the  average  home  during  the 
winter  months  by  the  shrinking  of  the  woodwork  and  furniture. 
The  absorption  of  the  moisture  from  the  building  which  is  usually 
termed  "  drying  out/'  causes  the  joints  in  the  floors  and  casements 
to  open,  doors  to  shrink  until  they  fail  to  latch  and  drawers  that 
have  opened  with  difficulty  during  the  summer  then  work  freely. 

Winter  time  is  the  season  of  prevalent  colds,  chaps  and  rough- 
ness of  the  skin,  not  so  much  on  account  of  cold  weather  as  be- 
cause of  dry  air.  The  skin  which  is  normally  moist  is  kept  dry 
by  constant  evaporation  with  the  attending  discomfort  of  an 
irritated  surface  and  the  results  which  follow. 

The  humidity  of  the  air  in  which  we  live  and  on  which  we 
depend  for  life  has  much  to  do  with  the  bodily  comfort  we  derive 
in  existence,  and  is  suspected  of  being  the  cause  of  many  physical 
ailments.  Ventilation  engineers  not  only  recognize  this  con- 
dition but  have  found  means  of  controlling  it.  It  is  possible 
to  so  control  atmosphere  temperature  and  humidity  of  buildings 
as  to  produce  any  desired  condition. 

Humidity  of  the  Air. — The  amount  of  water  vapor  in  the  air  is 
called  the  humidity  of  the  air.  It  may  vary  from  a  fraction  of  a 
grain  per  cubic  foot  in  extremely  cold  weather,  to  20  grains  per 
cubic  foot  during  the  occasional  hot  weather  of  summer. 

Since  the  amounts  of  moisture  that  air  will  hold  depends  on 
its  temperature,  and  as  the  air  is  ordinarily  only  partly  saturated, 
the  varying  amount  of  moisture  are  expressed  either  as  relative 
humidity  and  stated  in  per  cent,  saturation  or  in  the  actual  weight 
of  water  in  grains  per  cubic  foot  and  known  as  absolute  humidity. 

196 


ATMOSPHERIC  HUMIDITY  197 

The  relative  humidity  of  the  atmosphere  is  the  amount  of 
moisture  contained  in  a  given  space  as  compared  with  the  amount 
the  same  air  could  possibly  hold  at  that  temperature.  Warm 
air  will  hold  more  moisture  than  the  same  air  when  cold.  Air 
absorbs  water  like  a  sponge  to  a  point  of  saturation.  When  the 
air  is  filled  with  moisture,  any  change  which  takes  place  to  reduce 
the  temperature  also  reduces  its  capacity  to  hold  the  water 
vapor  and  the  excess  is  deposited  as  dew.  This  supersaturation 
ordinarily  takes  place  near  things  which  lose  their  heat  faster 
than  the  surrounding  air  and  the  nearest  colder  surface  acts  as  a 
condenser  to  receive  the  drops  of  dew.  Grass  being  in  convenient 
position  is  the  commonest  receptacle  for  dew  formation.  If  the 
dew  forms  in  the  air  it  falls  as  rain,  but  if  the  temperature  of  the 
dew-point  is  below  freezing,  the  dew  immediately  freezes  and 
snow  is  the  result. 

In  the  consideration  of  problems  that  involve  atmospheric 
moisture,  both  relative  and  absolute  humidity  are  factors  of 
common  use,  that  are  capable  of  exact  determination.  The  rela- 
tive humidity  of  the  air  is  most  readily  determined  and  as  it  ex- 
presses the  state  of  the  atmosphere  in' which  plants  and  animals 
live  and  thrive,  as  opposed  to  other  conditions  of  humidity  in 
which  they  sometimes  sicken  and  die,  it  is  one  of  the  indicators 
of  the  quality  of  atmospheric  air^ 

In  the  subject  of  ventilation,  which  is  undertaken  later,  it  will 
be  found  that  a  definite  knowledge  of  atmospheric  humidity  has 
much  to  do  with  the  successful  operation  of  ventilation  apparatus. 
Most  people  recognize  the  "balmy  air  of  June"  without  realizing 
just  why  at  the  same  temperature  other  seasons  are  not  so  delight- 
ful. In  reality  it  is  the  condition  of  atmospheric  humidity 
combined  with  an  agreeable  temperature  that  gives  the  kind  of 
air  in  which  we  find  the  greatest  degree  of  comfort. 

The  effect  of  moderately 'warm  humid  air  is  that  of  higher 
temperature  than  the  thermometer  indicates.  When  the  atmos- 
phere is  near  the  point  of  saturation,  the  evaporation  which 
usually  goes  on,  from  the  surface  of  the  body,  practically  ceases. 
In  summer  time  a  temperature  of  85°F.  with  relative  humidity 
of  90  .per  cent,  saturation  seems  warmer  than  a  temperature  of 
100°  at  40  per  cent,  saturation,  because  of  the  cooling  effect 
produced  by  the  increased  evaporation  due  to  the  drier  air. 


198  MECHANICS  OF  THE  HOUSEHOLD 

In  winter,  when  most  of  the  time  is  spent  indoors,  in  an  atmos- 
phere that  is  very  dry,  the  sensation  of  discomfort  produced  by 
the  lack  of  humidity  oftentimes  leads  to  physical  derangements 
that  would  never  appear  under  more  desirable  conditions.  The 
cause  of  many  ailments  of  the  nose,  throat  and  lungs  during  the 
winter  months  is  attributed  by  physiologists  to  breathing  almost 
constantly  the  dry  vitiated  indoor  air.  The  cause  of  dry  air  in 
buildings  is  not  difficult  to  explain ;  it  is  a  great  deal  more  difficult 
to  realize  that  the  lack  of  water  breeds  so  much  discomfort. 

In  order  to  express  the  condition  of  humidity  that  may  exist 
in  the  average  dwelling,  office  or  school-room  during  the  winter, 
it  is  most  convenient  to  refer  to  the  results  of  varying  atmospheric 
conditions  that  are  given  in  Table  1 — Properties  of  Air — which 
appears  below.  In  the  second  column  of  the  table,  under  the 
heading  " Weight  of  vapor  per  cubic  foot  of  saturated  air," 
will  be  found  the  amount  of  moisture  in  grains  per  cubic  foot 
that  will  be  required  to  humidify  air  at  different  temperatures. 
It  will  be  seen  that  at  10°  the  air  will  contain,  when  fully  saturated, 
only  1.11  grains  of  water,  while  at  70°  temperature  the  same  air 
would  hold  8  grains  of  water.  These  amounts  will  be  found  in  the 
column  opposite  the  temperature  readings.  It  is  at  once  evident 
that  when  saturated  air  at  10°  is  raised  to  normal  temperature 
70°,  the  original  amount  of  jnoisture  is  contained  in  an  at- 
mosphere capable  of  holding  8  grains  of  water.  Its  relative 

humidity  will  therefore  be  —  r-»  practically  14  per  cent,  satur- 

o 

ated.     Unless  moisture  is  received  by  the  air  from  some  other 
source  this  condition  will  produce  a  very  dry  atmosphere. 

The  normal  atmospheric  temperature  of  70°F.  with  a  relative 
humidity  of  50  to  60  per  cent,  saturation  produces  a  condition 
that  is  one  of  agreeable  warmth  to  the  average  person  in  health 
and  is  recognized  as  the  atmosphere  most  desirable.  To  some, 
this  state  of  temperature  and  humidity  is  that  of  too  much 
warmth  and  a  temperature  of  68°,  with  the  same  humidity,  is 
most  agreeable.  At  the  same  temperature,  a  reduction  of  the 
humidity  to  20  per  cent,  saturation  will  produce  a  feeling  of  dis- 
comfort and  the  sensation  will  be  that  of  a  lack  of  heat.  The 
cause  for  this  latter  feeling  is  due  to  excessive  evaporation  of 
moisture  from  the  body. 


ATMOSPHERIC  HUMIDITY 


199 


TABLE  I. — PROPERTIES  OF  AIR 


Tempera- 
ture of  the 
air 

Weight  of 
vapor  per 
cubic  foot  of 
saturated 
air 

Weight  of 
cubic  foot  of 
saturated 
air 

Tempera- 
ture of  the 
air 

Weight  of 
vapor  per 
cubic  foot  of 
saturated 
air 

Weight  per 
cubic  foot  of 
saturated 
air 

Fahrenheit 

Grains 

Grains 

Fahrenheit 

Grains 

Grains 

10° 

1.11 

589.4 

41° 

3.19 

550.8 

11 

1.15 

588.1 

42 

3.30 

549.6 

12 

1.19 

586.8 

43 

3.41 

548.4 

13 

1.24 

585.5                44 

3.52 

547.2 

14 

1.28 

584.2                 45 

3.64 

546.1 

15 

1.32 

582.9                 46 

3.76 

544.9 

16 

1.37 

581.6 

47 

3.88 

543.7 

17 

1,41 

580.3 

48 

4.01 

541.3 

18 

1.47 

579.1                49 

4.14 

542.5 

19 

1.52 

577.8 

50 

4.28 

540.2 

20 

1.58 

576.5 

51 

4.42 

539.0 

21 

1.63 

575.3                52 

4.56 

537.9 

22 

1.69 

574.0                53 

4.71 

536.7 

23 

1.75 

572.7                54 

4.86 

535.5 

24 

1.81 

571.5 

55 

5.02 

534.4 

25 

1.87 

570.2 

56 

5.18 

533.2 

26 

1.93 

569.0                57 

5.34 

532.1 

27 

2.00 

567.7                58 

5.51 

534.9 

28 

2.07 

566.5 

59 

5.69 

529.8 

29 

2.14 

565.3 

60 

5.87 

528.6 

30 

2.21 

564.1 

61 

6.06 

527.0 

31 

2.29 

562.8 

62 

6.25 

526.3 

32 

2.37 

561.6 

63 

5.45 

525.2 

33 

2.45 

566.4 

64 

6.65 

524.0 

34 

2.53 

559.2 

65 

6.87 

522.0 

35 

2.62 

558.0 

66 

7.08 

521.7 

36 

2.71 

556.8 

67 

7.30 

520.0 

37 

2.80 

555.6 

68 

7.53 

519.4 

38 

2.89 

554.4 

69 

7.76 

518.3 

39 

2.99 

553.2 

70 

8.00 

517.2 

40 

3.09 

552.0 

The  evaporation  of  moisture  is  always  accompanied  with  the 
loss  of  heat  required  to  produce  such  change  of  condition.  This 
is  known  as  the  heat  of  vaporization  and  represents  a  definite 
amount  of  heat  that  is  used  up  whenever  water  is  changed  into 
vapor.  No  matter  what  its  temperature  may  be — whether  hot 


200  MECHANICS  OF  THE  HOUSEHOLD 

or  cold — when  water  is  vaporized,  a  definite  amount  of  heat  is 
required  to  change  the  water  into  vapor. 

Water  may  be  evaporated  at  any  temperature;  even  ice  evapo- 
rates. A  common  instance  of  the  latter  is  that  of  wet  clothes 
which  " freeze  dry"  in  winter  weather  when  hung  on  the  clothes 
line.  The  rate  at  which  evaporation  takes  place  depends  on  the 
dryness  of  the  surrounding  air  and  the  rapidity  of  its  motion. 
In  dry  windy  weather  evaporation  is  most  rapid. 

As  before  stated,  whenever  water  evaporates — at  no  matter 
what  temperature — a  definite  quantity  of  heat  is  necessary  to 
change  the  water  into  vapor.  The  exact  amount  of  heat  required 
to  produce  this  change  varies  somewhat  with  the  temperature 
and  atmospheric  pressure  but  it  always  represents  a  large  loss 
of  heat.  At  the  boiling  point  of  water  (212°F.)  the  heat  of 
vaporization  is  970  B.t.u.  for  each  pound  of  water  evaporated, 
but  at  a  lower  temperature  it  is  greater  than  that  amount.  At 
the  temperature  of  the  body  (98.6°)  the  heat  necessary  to  evapo- 
rate a  pound  of  moisture  from  its  surface  is  1045  B.t.u. 

It  is  the  absorption  of  heat  due  to  evaporation  that  cools  the  air 
of  a  sprinkled  street.  The  more  rapid  the  evaporation  the  more 
pronounced  is  the  decline  of  temperature  in  the  immediate  vicin- 
ity. The  same  effect  fs  produced  when  moisture  is  evaporated 
from  the  surface  of  the  body.  The  acceleration  of  evaporation 
caused  by  a  breeze  or  the  blast  of  air  from  an  electric  fan  is  that 
which  produces  the  chilling  sensation  to  the  body.  During 
winter  weather  the  effect  of  the  cold  wind  is  rendered  more  severe 
by  evaporation  of  moisture  from  the  body.  In  health,  the  body 
being  in  a  slightly -moist  condition,  the  evaporation  which  goes 
on  from  its  surface  is  what  keeps  it  cool  in  warm  weather,  but 
if  on  account  of  excessive  dryness  of  the  surrounding  air  the 
evaporation  is  very  rapid,  a  sensation  of  cold  is  the  result. 

Not  only  does  excessively  dry^air  produce  the  sensation  of 
chilliness  but  the  loss  of  heat  from  the  body  due  to  sudden  or 
long  exposure  effects  the  general  health  and  is  conducive  to  chills 
that  are  followed  by  fever.  In  health  the  temperature  of  the 
body  is  constant  and  normally  98.6°F. ;  any  condition  that  reduces 
that  temperature  tends  toward  a  lowering  of  vitality  and  the 
consequent  inability  to  withstand  the  attack  of  disease.  In  a 
very  dry  atmosphere  the  skin,  instead  of  being  slightly  moist,  is 


ATMOSPHERIC  HUMIDITY  201 

kept  dry,  the  result  of  which  is  the  irritation  that  produces  chaps 
and  roughness  of  the  surface. 

Reports  of  the  U.  S.  Weather  Department  show  that  the  relative 
humidity  of  Death  Valley,  which  is  the  driest  and  hottest  known 
country,  during  the  driest  period  of  the  year — between  May  and 
September — averages  15.5  per  cent,  saturation.  In  winter, 
many  buildings,  particularly  offices  and  school  buildings  are  not 
far  from  that  atmospheric  condition,  constantly.  Under  the 
usual  conditions  of  houSe  heating,  there  is  an  almost  absolute 
lack  of  means  to  give  moisture  to  the  air.  Almost  without 
exception  steam-heating  plants  and  hot-water  heating  plants 
in  office  buildings  and  dwellings  are  without  any  provision  for 
changing  the  atmospheric  humidity. 

In  school  buildings  that  are  not  kept  under  a  more  desirable 
condition  of  temperature  and  humidity,  the  general  health  is 
impaired  and  the  behavior  of  the  pupils  very  markedly  influenced. 
The  tension  of  a  school-room  full  of  fidgety  nervous  children  can 
be  very  promptly  and  greatly  reduced  by  the  introduction  of 
water  vapor  into  the  air  to  50  per  cent,  saturation. 

All  modern  school  buildings,  auditoriums,  etc.,  are  provided — 
aside  from  the  heating  plants — with  means  of  ventilating  in 
which  the  entering  air  is  washed  and  humidified  to  the  desired 
degree,  before  being  sent  into  the  rooms. 

The  popular  conception  of  the  hot-air  furnace  method  of  heat- 
ing is  that  it  produces  particularly  dry  air,  when  in  reality  it  is 
the  only  type  of  house-heating  plant  in  which  any  provision  is 
made  for  adding  water  to  the  air.  These  furnaces  are  usually 
furnished  with  a  water  reservoir  by  use  of  which  the  humidity 
may  be  raised  to  a  desirable  point. 

Much  of  the  water  which  enters  the  air  of  the  average  home, 
during  winter  weather,  comes  from  the  evaporation  that  goes  on 
in  the  kitchen.  Usually  on  wash  days  the  humidity  is  raised  to 
a  marked  degree  and  that  day  is  commonly  followed  by  a  short 
period  of  agreeable  atmospheric  condition.  The  arrangement 
of  many  houses  is  such  that  a  much-improved  condition  of  hu- 
midity might  be  obtained  from  the  kitchen  by  continuous  evapo- 
ration of  water  from  a  tea-kettle. 

The  prevailing  impression  seems  to  exist  that  when  air  is 
heated,  it  loses  its  moisture.  In  reality,  air  that  is  heated  only 


202 


MECHANICS  OF  THE  HOUSEHOLD 


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204  MECHANICS  OF  THE  HOUSEHOLD 

attains  a  condition  in  which  its  capacity  for  containing  moisture 
is  increased.  If  after  being  heated  to  a  high  degree — and  is 
relatively  very  dry — the  air  is  reduced  to  its  original  temperature, 
the  amount  of  moisture  will  be  the  same  as  was  originally  con- 
tained. In  heating  houses  with  hot  air,  the  seemingly  dry  con- 
dition is  usually  due  to  temperature  alone.  When  a  hot-air 
furnace  is  provided  with  the  customary  reservoir  for  moistening 
the  discharged  air,  it  may  be  made  to  produce  excellent  conditions 
of  atmospheric  humidity.  The  heated  air  readily  absorbs  the 
water  evaporated  in  the  furnace  from  the  water  reservoir  and 
enters  the  rooms  as  relatively  dry  air  but  containing  more  mois- 
ture than  the  outside  air;  when  it  has  been  reduced  in  temperature 
by  mixing  with  the  cooler  air  of  the  house,  its  moisture  content 
remains  unaltered  and  at  the  lower  temperature  its  relative 
humidity  is  increased. 

Relative  Humidity. — Suppose  that  on  a  damp  day  the  outside 
temperature  is -50°  and  that  the  atmosphere  is  90  per  cent, 
saturated.  *The  air  that  comes  into  the  house  at  this  temperature 
and  humidity  is  heated  to -70°.  The  rise  of  temperature  gives 
the  air  the  property  of  absorbing  additional  moisture  so  that  the 
relative  humidity  which  was  90  per  cent,  is  now  much  less. 
From  the  table  relative  humidity,  will  be  seen. that  at  50° 
temperature*  and  90-  per  cent,  saturation  the  air  contains  3.67 
grains  of  moisture.  When  the  air  is  heated  to  70°,  it  still  con- 
tains the  original  amount  of  moisture  but  its  relative  humidity 
has  decreased  with  the  change  of  temperature.  It  is  really  the 
amount  of  moisture  present — 3. 67  grains — divided  by  the  amount 
necessary  to  saturate  the  air  at  70°,  which  is  8  grains;  this  gives 
approximately  a  relative  humidity  40  per  cent,  saturation. 

As  the  temperature  goes  lower,  less  and  less  moisture  is  required 
to  saturate  the  air.  If  saturated  air  at  0°F.,  which  contains 
0.48  grain  of  water,  is  raised  to  70°F. — :where  8  grains  of  water  is 
required  for  saturation — the  percentage  of  saturation  would  be 

0.48 

— g-or  6  per  cent. 

The  Hygrometer. — The  instrument  most  commonly  employed 
for  determining  atmospheric  humidity  is  the  hygrometer. 
This  appliance  is  composed  of  two  thermometers  mounted  in  a 
frame  with  a  vessel  for  holding  water.  One  of  the  thermometers 


ATMOSPHERIC  HUMIDITY  205 

is  intended  to  register  the  temperature  of  the  air  and  is  called  the 
dry-bulb  thermometer.  The  bulb  of  the  other  —  the  wet-bulb 
thermometer  —  is  covered  with  a  piece  of  cloth  or  other  porous 
material  which  is  kept  saturated  with  water,  absorbed  from 
the  water  holder.  The  dryness  of  the  air  is  indicated  in  the 
wet-bulb  thermometer  by  the  decline  of  temperature  due  to 
evaporation. 

The  rate  of  evaporation  from  the  wet-bulb  covering  will  ^ary 
with  the  humidity  and  if  the  air  is  very  dry  the  wet-bulb  thermom- 
eter will  register  a  temperature  several  degrees 
below  that  of  the  other  thermometer.  If 
the  air  is  saturated  with  moisture,  no  evapo- 
ration will  take  place  and  the  thermometers 
will  read  alike.  The  relative  humidity  of  the 
air  as  indicated  by  the  readings  of  the  ther- 
mometers is  taken  directly  from  a  humidity 
table.  The  table  is  made  to  suit  any  condi- 
tion of  atmospheric  humidity  and  the  deter- 
minations require  no  calculation. 

Fig.  157  shows  the  U.  S.  Weather  Bureau 
pattern  hygrometer  such  as  is  used  at  the 
weather  stations.  The  wet-bulb  thermom- 
eter has  a  muslin  or  knitted  silk  covering 
which  dips  into  a  metal  water  cup  as  shown 
in  the  figure.  It  is  important  that  the 
covering  of  the  wet  bulb  be  kept  in  good 
condition.  The  evaporation  of  the  water 
from  the  covering  leaves  in  the  meshes  par-  gr^e°ter 
tides  of  solid  matter  that  were  held  in  solu-  Weather  Bureau 


tion  in  the  water.     The  accumulation  of  the 

solids    ultimately    prevent    the    water    from    humidity. 

thoroughly  wetting  the  wick. 

An  observation  consists  in  reading  the  two  thermometers  and 
from  the  difference  between  the  wet-bulb  reading  and  that  of  the 
dry-bulb,  the  relative  humidity  is  taken  directly  from  the  table. 
To  illustrate,  suppose  that  the  dry-bulb  thermometer  reads  60° 
and  that  the  wet-bulb  reads  56°.  The  difference  between  the 
two  readings  is  4°.  In  the  table  of  relative  humidity  on  page 
202,  60°  is  found  in  the  column  headed,  Air  temp,  t,  and  opposite 


206 


MECHANICS  OF  THE  HOUSEHOLD 


that  number  in  the  column  headed  4  is  78,  which  indicates  that 
under  the  observed  conditions  the  air  is  78  per  cent,  saturated 
with  moisture.  This  table  is  suited  for  air  temperatures  from 
35°F.  to  80°F.  and  depressions  of  the  wet-bulb  thermometer 
from  1°F.  to  20°F.  The  table,  therefore,  has  a  range  of  variations 
which  will  admit  humidity  determinations  for  all  ordinary 
conditions. 

The  Hygrodeik. — In  Fig.  158  is  shown  a  form  of  hygrometer 
known  as  a  hygrodeik,  by  means  of  which  atmospheric  humidity 
may  be  determined  without  the  use  of  the  tables.  In  the  figure 

the  wet-bulb  and  dry-bulb  ther- 
mometers are  easily  recognized. 
A  glass  water  bottle  W  is  held 
to  the  base  of  the  instrument 
by  spring  clips  which  permit  its 
removal  to  be  filled  with  water. 
Between  the  thermometers  is  a 
diagram  chart  from  which  the 
atmospheric  humidity  is  taken. 
An  index  arm,  carrying  a  mov- 
able pointer  P,  permits  the  in- 
strument to  be  set  for  any  ob- 
served thermometer  readings. 

The  index  is  really  a  graphical 
method  of  expressing  the  figures 
given  in  the  table  on  pages  202- 
203.  In  the  picture  the  wet- 
bulb  thermometer  reads  65°,  the 
dry-bulb  thermometer  77°.  To 

determine  the  relative  humidity  under  these  conditions  the  mov- 
able arm  is  swung  to  the  left  and  the  pointer  P  placed  on  the 
left-hand  scale  at  the  line  65°.  The  arm  is  then  swung  to  the 
right  until  the  pointer  touches  the  downward  curving  line  begin- 
ning at  77°,  the  dry-bulb  reading.  The  lower  end  of  the  arm  H 
now  points  to  the  relative  humidity,  where  52  per  cent,  is  indi- 
cated by  the  scale  at  the  bottom  of  the  index. 

The  same  result  is  obtained  from  the  table  of  Relative  Humid- 
ity. The  readings  of  the  thermometers  in  the  figure  give  a 
difference  in  temperature  of  12°,  the  dry-bulb  thermometer 


FIG.  158. — The  hygrodeik  A  form 
of  hygrometer  in  which  relative  hu- 
midity is  found  directly  from  a  dia- 
gram. « 


ATMOSPHERIC  HUMIDITY  207 

reads  77°.  Referring  this  data  to  the  humidity  table,  the 
column  marked  12,  for  the  depression  of  the  wet-bulb  ther- 
mometer and  opposite  77°  in  the  air  temperature  column,  is 
found  53  which  indicates  the  per  cent,  of  saturation.  The 
hygrodeik  gives  further  the  temperature  of  the  dew-point,  on 
the  scale  to  the  right;  and  the  absolute  humidity  may  be  found 
by  following  the  upward  curving  line  nearest  the  pointer,  at  the 
end  of  which  line  is  given  the  value  in  grains 
of  moisture  per  cubic  foot.  The  hygrodeik 
or  other  instrument  of  the  kind  is  very  largely 
used  in  places  where  relative  humidity  is 
regularly  observed  by  those  of  limited  ex- 
perience, as  in  school-rooms,  auditoriums, 
etc.  Such  records  are  not  intended  to  be 
perfectly  accurate  and  the  readings  of  the 
hygrodeik  are  very  well-suited  for  the 
purpose. 

In  using  the  hygrometer  and  the  hygrodeik 
the  instruments  are  stationary;  they  are 
usually  hung  on  the  wall  in  a  convenient 
location  for  observation  and  are  placed  to 
avoid  accidental  drafts  in  order  that  the 
conditions  surrounding  the  observation  may 
be  the  same  at  all  times.  The  evaporation 
which  takes  place  from  the  wet  bulb  is  due 
to  natural  convection  and  does  not  always 
reach  the  maximum  amount.  The  evapora- 
tion  is  furthermore  influenced  by  accidental  Bureau  type;  for  accu- 
variations  and  consequently  the  results  can-  ;£££?&*! 
not  be  considered  exact. 

Under  conditions  that  demand  more  exact  humidity  records 
than  are  obtainable  with  hygrometer,  the  psychrometer  furnishes 
means  of  making  more  accurate  observation.  The  psychrometer 
shown  in  Fig.  159  is  of  the  form  used  by  the  U.  S.  Weather 
Department.  Like  the  hygrometer,  it  is  composed  of  a  wet- 
bulb  and  a  dry-bulb  thermometer  but  no  water  cup  is  attached 
to  the  instrument  for  moistening  the  wick  of  the  wet  bulb.  When 
ready  for  use  the  wick  is  wet  with  water  before  each  observation. 

The  greater  accuracy  to  be  attained  by  the  use  of  this  instru- 


208  MECHANICS  OF  THE  HOUSEHOLD 

ment  is  on  account  of  the  maximum  evaporation  which  is  ob- 
tained from  the  wet  bulb  for  any  atmospheric  condition.  The 
evaporation  which  takes  place  from  the  wet-bulb  thermometer 
in  quiet  air  is  not  so  great  as  that  which  occurs  if  the  same  air  is  in 
motion.  In  moving  air,  however,  there  is  a  certain  maximum 
rate  beyond  which  no  further  evaporation  will  take  place. 

The  motion  of  the  air  may  be  produced  either  by  blowing  on 
the  bulb  with  a  fan  or  air  blast,  or  by  whirling  the  thermometer. 
With  the  psychrometer  the  latter  method  is  used.  This  instru- 
ment is  provided  with  a  handle  which  is  pivoted  to  the  frame 
and  about  which  it  is  swung  to  produce  a  maximum  evaporation 
from  the  wick.  When  a  motion  of  the  air  is  attained  sufficient 

to  produce  a  saturated  atmosphere 
about  the  bulb,  the  temperature  will 
remain  constant. 

A  velocity  of  air  or  the  motion  of 
the  wet-bulb  thermometer  10  feet  per 
second  is  that  usually  taken  as  the 
rate  for  observation  and  the  swinging 
is  kept  up  3  or  4  minutes  or  until  the 
temperature  of  the  wet-bulb  thermom- 
eter remains  stationary. 

Then  the  temperature  of  each  ther- 
FIG.  leo.^iJh^grometer.     mometer    is    read    and    the    humidity 

found  in  the  table.     Relative  humidity 

determinations  may  be  made  at  temperatures  below  the  freez- 
ing point  if  sufficient  precaution  is  taken  in  the  observations. 
When  the  instrument  is  not  in  use,  it  is  kept  in  the  metallic 
case  shown  in  the  picture,  to  protect  it  from  injury. 

Dial  Hygrometers. — Various  forms  of  hygrometers  are  in  use, 
in  which  a  pointer  is  intended  to  indicate  on  a  dial  the  percent- 
age of  atmospheric  humidity.  That  shown  in  Fig.  160  is  one  of 
the  common  forms.  Instruments  of  this  kind  depend  for  their 
action  on  the  absorptive  property  of  catgut  or  other  materials 
that  are  sensitive  to  the  moisture  changes  of  the  air. 

These  instruments  give  fairly  accurate  readings  in  a  small 
range  for  a  limited  time,  but  they  are  apt  to  go  out  of  adjustment 
from  causes  that  cannot  be  controlled.  Unless  they  are  occasion- 
ally compared  with  a  standard  humidity  determination,  their 


ATMOSPHERIC  HUMIDITY 


209 


readings  cannot  be  relied  upon  for  definite  amounts  of  atmos- 
pheric moisture. 

The  Swiss  Cottage  "Barometer."— Fig.  161  is  one  of  the 
instruments  of  absorptive  class  that  are  sometimes  used  as 
weather  indicators.  The  images  which  occupy  the  openings  in 
the  cottage  are  so  arranged  that  with  the  approach  of  damp 
weather  the  man  comes  outside  and  at  the  same  time  the  woman 
moves  back  into  the  house.  In  fair  weather  the  reverse  move- 
ment takes  place.  The  figures  are  mounted  on  the  opposite 
ends  of  a  light  stick  which  is  fastened  to  an  upright  pillar.  The 
movement  of  the  images  is  caused  by  the 
change  in  length  of  a  piece  of  catgut  which 
is  secured  to  the  pillar  and  also  to  the  frame 
of  the  house.  Any  change  in  atmospheric 
humidity  causes  a  contraction  or  elonga- 
tion of  the  catgut  which  moves  the  pillar 
and  with  it  the  images. 

Since  stormy  weather  is  accompanied 
by  a  high  degree  of  humidity  and  fair 
weather  is  attended  with  dry  atmosphere, 
the  movement  of  the  images  indicates  in 

,          .,  FIG.  161. — Swiss   cot- 

SOme  degree  the  weather  changes;  but  the    tage"  Barometer."  This 
device  is  not  in  anv  way  influenced  by    device   is  arranged    to 

,       .  11-  snow    the    condition    of 

atmospheric  pressure  and  hence  is  not  a    atmospheric     humidity 

barometer.  ky  the  movement  of  the 

.  images.     It  is  not  really 

Dew-point.  —Dew  is  formed  whenever  a  barometer, 
falling  temperature  of  the  air  passes  the 
point  where  saturation  occurs.  The  reduction  of  the  tempera- 
ture of  air  raises  the  relative  humidity  because  of  the  dimin- 
ished capacity  to  contain  moisture.  As  the  temperature  declines 
there  will  come  a  point  at  which  the  air  is  saturated  and  any 
further  decrease  of  temperature  will  cause  supersaturation.  At 
this  point  the  moisture  will  be  deposited  on  the  cooler  surfaces 
in  the  form  of  drops.  The  temperature  at  which  dew  begins 
to  form  is  known  as  the  dew-point.  The  sweating  of  cold 
water  pipes,  the  dew  that  forms  on  a  water  glass  and  other 
relatively  cold  surfaces  is  caused  by  a  temperature  below  the 
dew-point  of  the  air. 

The    temperature    at  which  dew  forms  will  depend  on  the 

14 


210 


MECHANICS  OF  THE  HOUSEHOLD 


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212  MECHANICS  OF  THE  HOUSEHOLD 

amount  of  moisture  present  in  the  air,  but  with  a  definite  humid- 
ity and  air  pressure  it  will  always  occur  at  the  same  temperature. 
If  the  dew-point  is  above  freezing,  the  dew  will  form  as  drops  of 
water,  but  if  it  is  at  or  slightly  below  the  freezing  point,  the  dew 
will  appear  as  frost.  White  frost  is  formed  when  the  dew-point 
is  only  a  few  degrees  below  the  freezing  point.  A  Black  frost 
occurs  when  the  atmospheric  humidity  is  so  low  that  dew  does 
not  form  until  the  temperature  is  much  below  the  freezing  point. 

To  Determine  the  Dew-point. — The  dew-point  may  be  found 
by  a  number  of  methods,  usually  described  in  works  on  physics 
but  practical  determinations  are  made  with  a  hygrometer  or 
psychrometer  and  a  dew-point  table.  Accurate  determinations 
must  be  made  by  the  use  of  the  psychrometer;  those  made  by 
the  hygrometer  are  approximate.  Suppose  the  reading  of  the 
dry-bulb  thermometer  is  68  and  that  this  is  designated  as  t'} 
at  the  time  the  wet-bulb  temperature  is  57  and  is  called  t' . 
The  depression  of  the  wet  bulb  for  these  temperatures  (t-f)  is 
11°.  In  the  dew-point  table  above  is  found  in  the  dry-bulb 
column,  opposite  this  number  in  the  column  headed  11 — under 
depression  of  the  wet-bulb  thermometer — is  49,  which  is  the 
dew-point  for  the  observed  conditions. 

As  another  illustration,  suppose  the  dry  bulb  of  the  psychrome- 
ter marks  65°  and  the  wet  bulb  indicates  56°F.;  then  65-56 
equals  9°  of  the  cold  produced  by  evaporation.  The  dew-point 
is  determined  in  exactly  the  same  way  as  with  the  hygrometer. 
Opposite  65,  in  the  dry-bulb  column  of  the  dew-point  table, 
under  the  column  of  differences  marked  9,  is  found  the  dew- 
point  for  the  observed  conditions.  This  is  49°  at  which  tempera- 
ture dew  will  begin  to  form. 

Frost  Prediction. — The  formation  of  dew  is  always  attended 
with  a  liberation  of  heat — the  heat  of  vaporization — which  tends 
to  check  the  further  decline  of  temperature.  The  heat  thus 
developed  is  usually  sufficient  to  prevent  the  fall  of  temperature 
beyond  a  very  few  degrees,  but  at  times  when  there  is  little 
moisture  in  the  air  the  fall  of  several  degrees  of  temperature  is 
necessary  before  the  heat  liberated  by  the  forming  dew  bal- 
ances the  heat  lost  by  radiation  and  the  temperature  remains 
stationary. 


ATMOSPHERIC  HUMIDITY  213 

This  condition  of  things  was  pointed  out  many  years  ago  by 
Tyndall,  who  in  his  book  on  "Heat"  states:  "The  removal  for  a 
single  summer's  night  of  the  aqueous  vapor  which  covers  England 
would  be  attended  by  the  destruction  of  every  plant  which  a 
freezing  temperature  would  kill." 

The  frosts  of  late  spring  and  early  fall  which  occur  at  times 
of  dry  air  and  cloudless  sky  are  often  caused  by  local  conditions 
that  are  not  forecasted  by  the  weather  department  and  often 
may  be  successfully  combated. 

At  the  time  of  suspected  frost,  the  temperature  of  the  dew- 
point  in  relation  to  the  freezing  point  determines  the  probability 
of  a  freezing  temperature.  If  the  dew-point  occurs  at  10°  or 
more  above  the  freezing  point  there  will  be  little  danger  of  a 
killing  frost.  As  the  difference  in  temperature  between  the  dew- 
point  and  the  frost  point  decreases,  the  danger  of  frost  increases. 
If  the  dew-point  fells  at  the  freezing  point,  frost  is  a  certainty. 

In  using  the  table  on  page  214,  the  open  diagonal  line  may  be 
considered  the  danger  line  and  any  dew-point  falling  below  the 
temperature  thus  indicated  will  be  considered  dangerously  near 
the  frost  point.  This  table  differs  from  the  other  dew-point 
table  only  in  the  range  of  temperature.  The  dew-point  is  found 
in  exactly  the  same  way  as  before.  In  the  use  of  the  psychrome- 
ter  and  table  as  a  means  of  frost  prediction  it  is  first  necessary 
to  make  a  reading  of  the  wet-bulb  and  dry-bulb  temperature 
described  above.  The  dry-bulb  reading  is  found  in  the  left- 
hand  column  of  the  table;  then  follow  the  horizontal  line  opposite 
the  figure,  till  the  perpendicular  column  is  reached  indicating 
the  difference  in  reading  between  the  dry  and  wet  bulb.  The 
number  at  the  meeting  will  be  the  temperature  of  the  dew-point. 
For  example,  suppose  the  dry  bulb  stands  at  65°  and  the  wet 
bulb  at  55°,  the  difference  being  10°  and  dew-point  under  these 
conditions  will  be  47°. 

If  the  dew-point  is  10°  or  more  above  the  freezing  point  there 
is  no  danger  of  a  frost,  but  if  the  conditions  are  such  as  to  give  a 
temperature  difference  less  than  10°  above  the  freezing  point 
there  would  be  danger.  If  the  dew-point  falls  below  the  open 
diagonal  line  of  the  table  there  is  danger  and  that  danger  in- 
creases as  the  difference  in  degrees  between  the  freezing  point 
and  the  dew-point  becomes  less. 


214 


MECHANICS  OF  THE  HOUSEHOLD 


As  another  illustration,  suppose  that  at  sunset  at  the  time  of 
suspected  frost  the  dry-bulb  thermometer  read  54  and  the 
depression  of  the  wet  bulb  showed  10°.  Referring  to  the  table 
it  will  be  seen  that  for  these  conditions  the  dew-point  falls  at  33 
which  is  only  1°  above  the  freezing  point.  It  is  highly  probable 
that  frost  would  form. 

DEW-POINT  TABLE  FOR  FROST  PREDICTION 
Depression  of  the  wet-bulb  thermometer 


Dry- 
bulb 
temp. 

l 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

70 

69 

67 

66 

64 

62 

61 

59 

57 

55 

53 

51 

49 

47 

69 

68 

66 

64 

63 

61 

59 

58 

56 

54 

52 

50 

48 

46 

68 

67 

65 

63 

62 

60 

58 

57 

55 

53 

51 

49 

46 

44 

67 

66 

64 

62 

61 

59 

57 

55 

54 

52 

50 

47 

45 

43 

66 

64 

63 

61 

60 

58 

56 

54 

52 

50 

48 

46 

44 

65 

63 

62 

60 

59 

57 

55 

53 

51 

49 

47 

45 

42 

41 

64 

62 

61 

59 

57 

56 

54 

52 

50 

48 

46 

43 

40 

63 

61 

60 

58 

56 

55 

53 

51 

49 

47 

44 

42 

41 

38 

62 

60 

59 

57 

55 

53 

52 

50 

48 

45 

43 

39 

37 

61 

59 

58 

56 

54 

52 

50 

48 

46 

44 

42 

41 

38 

35 

60 

58 

57 

55 

53 

51 

49 

47 

45 

43 

39 

36 

33 

59 

57 

56 

54 

52 

50 

48 

46 

44 

40 

38 

43 

32 

58 

56 

55 

53 

51 

49 

47 

45 

42 

41 

39 

36 

33 

30 

57 

55 

54 

52 

50 

48 

46 

44 

40 

37 

35 

31 

28 

56 

54 

53 

51 

49 

47 

44 

42 

41 

39 

36 

33 

30 

26 

55 

53 

52 

50 

48 

46 

43 

40 

37 

34 

31 

28 

25 

54 

52 

50 

49 

46 

44 

42 

41 

39 

36 

33 

30 

27 

23 

53 

51 

49 

47 

45 

43 

40 

37 

34 

31 

28 

25 

20 

52 

50 

48 

46 

44 

42 

41 

38 

36 

33 

30 

27 

23 

18 

51 

49 

47 

45 

43 

40 

37 

34 

31 

28 

25 

21 

16 

50 

48 

46 

44 

42 

41 

38 

36 

33 

30 

27 

23 

19 

14 

49 

47 

45 

43 

40 

37 

34 

31 

28 

25 

21 

17 

11 

48 

46 

44 

42 

41 

38 

36 

33 

30 

27 

23 

19 

14 

9 

47 

45 

43 

40 

37 

35 

32 

29 

25 

22 

17 

12 

6 

46 

44 

42 

41 

39 

36 

33 

30 

27 

24 

20 

15 

10 

3 

45 

43 

40 

37 

35 

32 

29 

26 

22 

18 

13 

7 

-1 

44 

42 

41 

39 

36 

33 

30 

27 

24 

20 

16 

11 

4 

-5 

40 

37 

35 

32 

29 

26 

23 

19 

14 

8 

1 

-9 

43 

41 

39 

36 

34 

31 

28 

25 

21 

17 

12 

6 

-2 

-15 

42 

40 

38 

35 

33 

29 

26 

23 

19 

15 

9 

3 

-6 

-22 

41 

39 

36 

34 

31 

28 

25 

22 

17 

13 

7 

0 

-11 

-32 

40 

38 

35 

33 

30 

27 

24 

20 

16 

11 

4 

-4 

-16 

-74 

39 

37 

34 

32 

29 

26 

22 

18 

14 

8 

2 

-8 

23 

38 

36 

33 

31 

28 

24 

21 

17 

12 

-6 

-1 

-12 

-35 

ATMOSPHERIC  HUMIDITY  215 

Prevention  of  Frost. — From  the  discussion  of  frost  formation 
it  is  evident  that,  the  temperature  of  the  dew-point  being  the 
determining  factor  in  its  probable  occurrence,  any  expedient  that 
may  be  used  either  to  increase  the  humidity  or  to  conserve  the 
radiation  of  heat  would  prevent  a  dangerous  decline  of  tempera- 
ture. Frost  prevention  is  practised  in  all  fruit-growing  regions 
and  the  method  pursued  depends  on  the  kind  of  vegetation  to 
be  protected. 

In  the  protection  of  orchards  the  use  of  smudge  pots  are  prob- 
ably the  commonest  means  for  preventing  the  loss  of  heat. 
The  object  is  to  create  a  cloud  of  smoke  over  and  about  the 
orchard  so  that  it  forms  a  protective  covering  which  prevents 
the  escape  of  the  heat. 

In  the  case  of  a  light  frost — that  is,  where  the  temperature 
falls  only  a  few  degrees  below  the  frost  point — the  plants  in  small 
gardens  and  flower  beds  may  be  prevented  from  freezing  by 
liberal  sprinkling  with  water.  This  is  done  to  raise  the  humidity 
of  the  atmosphere  surrounding  the  vegetation.  Most  vegetation 
withstands  the  temperature  at  the  freezing  point  without  particu- 
lar injury,  and  the  freezing  of  part  of  the  water  liberates  heat  in 
sufficient  quantity  to  prevent  a  further  decline  of  temperature. 
This  heat  liberated  on  the  freezing  of  water  is  described  in  physics 
as  the  heat  of  fusion  and  in  changing  part  of  the  water  into  ice 
sufficient  heat  is  liberated  to  check  the  further  fall  of  temperature. 

Humidifying  Apparatus. — Opportunity  for  adding  moisture, 
in  the  desired  quantity,  to  the  air  of  the  average  dwelling  is 
limited  to  the  evaporation  of  water  in  the  heating  plant,  from 
vessels  attached  to  the  radiators  or  that  which  goes  on  in  the 
kitchen.  Household  humidifying  plants  are  within  the  range 
of  possibility  but  there  is  not  yet  sufficient  demand  for  their 
use  to  make  attractive  their  manufacture. 

In  the  hot-air  furnace  a  water  reservoir  is  usually  a  part  of  the 
chamber  in  which  the  air  supply  is  heated.  The  water  in  the 
reservoir  is  heated  to  a  greater  or  lesser  degree,  depending  on  the 
temperature  of  the  furnace  and  vaporized  both  by  heat  and  by 
the  constantly  changing  air. 

In  the  use  of  a  steam  plant  or  hot-water  heating  plant  the 
opportunity  of  humidifying  the  air  is  very  limited.  One  method 
is  that  of  suspending  water  tanks  to  the  back  of  the  radiators 


216  MECHANICS  OF  THE  HOUSEHOLD 

from  which  water  is  vaporized.  While  this  method  is  fairly 
efficient  as  a  humidifier  it  is  inconvenient  and  therefore  apt  to  be 
neglected.  In  houses  heated  by  stoves  there  are  sometimes 
water  urns  attached  to  the  top  of  the  frame  which  are  intended 
for  the  evaporation  of  water  but  as  a  rule  they  are  not  of  sufficient 
size  to  be  of  appreciable  value. 

The  quantity  of  water  required  to  humidify  the  air  of  a  house 
will  depend  first,  on  the  temperature  and  humidity  of  the  out- 
side air;  second,  on  the  cubic  contents  of  the  building;  third, 
on  the  rate  of  change  of  air  in  the  building.  If  the  ventilation 
is  good  the  rate  of  atmospheric  change  is  rapid  and  the  amount 
of  water  in  consequence  must  be  correspondingly  increased. 

The  data  included  in  the  following  table  showing  the  relative 
humidity  and  amount  of  water  required  were  taken  from  a  seven- 
room  frame  dwelling  in  Fargo,  N.  D.,  during  particularly  severe 
winter  weather.  The  relative  humidity  determinations  were 
made  with  a  hygrodeik  each  day  at  noon.  The  house  was  heated 
by  a  hot-air  furnace  arranged  to  take  its  air  supply  from  the 
outside. 

The  air  supply  is  recorded  under  Cold-air  intake.  The  furnace 
was  provided  with  a  water  pan  for  humidifying  the  air  supply. 
The  amount  of  water  evaporated  each  day  is  recorded  in  the  col- 
umn headed  Evap.  in  24  hours.  The  outside  temperature 
ranged  from  —  12°F.  to  —  21°F.  The  weather  was  clear  and  calm 
except  the  last  day,  Jan.  12,  which  was  windy.  The  higher 
humidity  on  that  day  was  no  doubt  due  to  the  greater  amount 
of  heat  required  from  the  furnace  and  the  consequent  evaporation 
of  the  water  from  the  water  pan. 

The  humidity  determinations  made  by  a  hydrodeik,  as  before 
explained,  are  only  approximately  correct  but  sufficiently  exact 
for  practical  purposes.  The  temperature  is  given  in  degrees 
Fahrenheit. 

In  the  table  it  will  be  noticed  that  the  outside  air  was  used 
only  a  part  of  the  time  because  of  the  severity  of  the  weather. 
Attention  is  called  to  the  quantity  of  water  required  to  keep  the 
humidity  at  the  amount  shown.  This  averages  27J^  quarts 
per  day.  At  the  time  these  observations  were  made  the  physics 
lecture-room  at  the  North  Dakota  Agricultural  College  averaged 
18  to  20  per  cent,  saturation  during  class  hours,  with  observations 


ATMOSPHERIC  HUMIDITY 


217 


made  from  a  similar  instrument.  This  is  a  steam-heated  room 
with  only  accidental  means  of  adding  water  to  the  air.  The 
result  was  an  atmosphere  3^  per  cent,  above  that  of  Death 
Valley. 

HOT-AIR  FURNACE 
Readings  taken  at  12  o'clock  noon  each  day 


Date 

Temp, 
outside 

Wet 
bulb 

Dry 

bulb 

Per 

cent, 
satu- 
rated 

Evap.  In 
24  hours 
quarts  pints 

Cold-air  intake 

Dec.  13  

-13 

54° 

63° 

53 

Closed  8  a.m. 

Dec.  14  

-18 

55 

66 

47 

Open 

Dec.  15  

-20 

57 

68 

49 

21 

Closed  7  a.m. 

Dec   16. 

-18 

57 

67 

51 

20       1 

Closed  7  a.m. 

Dec   17 

-22 

58 

69 

48 

18       1 

Closed  7  a.m. 

Dec.  18  

-16 

55 

65 

51 

17    iy2 

Closed  6:  30  a.m. 

Dec.  19  

-10 

57 

68 

47 

20       1 

Closed  8  a.m. 

Dec.  20  

0 

59 

70 

49 

13         % 

Not  open  at  night 

Jan.  8     .... 

-12 

58 

71 

43 

18 

Closed 

Jan.  9  

-17 

57 

71 

39 

25 

Open  24  hours 

Jan.  10  

-16 

58 

69 

45 

27       1 

Open  10  hours 

Jan.  11 

-21 

60 

75 

40 

30 

Closed 

Jan.  12  

-15 

60 

73 

46 

30 

Closed 

The  amounts  of  water  evaporated  may  seem  large  to  those 
who  are  unaccustomed  to  quantitatively  consider  problems  in 
ventilation  but  the  small  amount  of  water  in  the  air  at  —21° 
must  produce  a  very  dry  atmosphere  when  it  is  raised  to  70°  in 
temperature. 

The  amount  of  moisture  in  air  at  20°K.  and  at  80  per  cent, 
humidity  is  only  1.58  grains  to  the  cubic  foot.  If  this  air  is 
now  raised  to  70°  the  moisture  will  still  be  1.58  grains  where 
there  should  be  4  grains  of  water  to  make  50  per  cent,  humid- 
ity. It  therefore  will  require  the  addition  of  practically  2.42 
grains  of  water  for  each  cubic  foot  of  entering  air  in  order  to 
bring  it  up  to  50  per  cent,  humidity. 

In  a  case  with  the  above  conditions  of  atmosphere,  suppose 
it  is  desired  to  know  the  amount  of  water  that  would  be  taken 
up  in  humidifying  the  air  for  a  school-room  of  size  to  accommodate 
40  pupils.  The  prescribed  quantity  of  air  for  this  purpose  is 


218  MECHANICS  OF  THE  HOUSEHOLD 

30  cubic  feet  per  minute  for  each  pupil.  The  air  is  to  be  main- 
tained at  a  humidity  50  per  cent,  saturated.  The  problem  will 
be  one  of  simple  arithmetic.  If  each  pupil  is  to  receive  30  cubic 
feet  of  air  per  minute  or  1800  cubic  feet  per  hour,  the  40  pupils 
receiving  1800  cubic  feet  per  hour  will  require  40  X  1800  =  72,000 
cubic  feet  of  air  per  hour.  To  each  cubic  foot  of  the  air  is  to  be 
added  2.74  grains  of  water,  72,000  X  2.42  =  164,240  grains  of 
water.  Reducing  this  to  pounds,  164,240  -f-  7000  =  23.46 
pounds  or  2.77  gallons  of  water  per  hour. 

In  practice  the  room  will  show  a  higher  amount  than  50  per 
cent,  humidity  with  this  addition  of  the  amount  of  water,  because 
of  the  water  vapor  that  is  exhaled  from  the  lungs  of  the  pupils. 
That  a  considerable  amount  of  water  vapor  is  added  to  the  atmos- 
phere by  breath  exhalation  is  made  evident  from  the  moisture 
condensed  by  breathing  on  a  cold  pane  of  glass.  In  any  unven- 
tilated  room  occupied  by  a  considerable  number  of  people  the 
humidity  is  thus  increased  a  very  noticeable  amount. 

The  change  in  humidity  of  the  air  in  a  closed  room  filled  with 
people  is  very  pronounced.  The  constant  exhalation  of  moisture 
from  the  lungs  is  sufficient  to  saturate  the  air  in  a  short  time. 
The  heavy  atmosphere  of  overcrowded,  unventilated  rooms  is 
due  to  moisture  exhalation,  body  odors  and  increased  carbonic 
acid  gas.  As  the  humidity  of  the  atmosphere  is  increased  a 
sensation  of  uncomfortable  warmth  is  the  result  of  the  lesser 
evaporation. 


CHAPTER  XI 
VENTILATION 

The  purity  of  air  in  any  habitable  enclosure  is  determined  by 
the  amount  of  CC>2  (Carbonic  acid  gas)  included  in  its  composi- 
tion. The  process  of  ventilation  is  that  of  adding  fresh  air  to 
the  impure  atmosphere  of  houses,  until  a  desirable  quality  is 
attained.  In  the  opinion  of  hygienists,  when  air  does  not  exceed 
6  to  8  parts  of  CC>2,  by  volume  in  10,000,  the  ventilation  is  desir- 
able. Ordinary  outdoor  air  contains  about  4  parts  of  CO2  to 
10,000,  while  very  bad  air  may  contain  as  high  as  80  parts  to  the 
same  quantity.  The  quantity  of  air  required  for  the  ventilation 
of  a  building  is  determined  by  the  number  of  people  to  be  pro- 
vided. The  amount  of  air  required  per  individual  per  hour 
necessary  to  produce  a  desired  condition  of  ventilation  is  deter- 
mined by  adopting  a  standard  of  purity  to  suit  the  prevailing 
circumstances. 

In  hospitals  where  pure  air  is  considered  of  greatest  impor- 
tance 4000  and  5000  cubic  feet  per  inmate  per  hour  is  not  uncom- 
mon. The  practice  of  supplying  30  cubic  feet  of  air  per  person 
per  minute  (1800  cubic  feet  per  hour)  seems  to  fulfill  the  average 
requirements.  It  is  the  amount  commonly  specified  for 
school-rooms. 

The  quantity  of  fresh  air  required  per  person  to  insure  good 
ventilation  will  depend  on  the  type  of  building  to  be  supplied 
and  varies  somewhat  with  different  authorities.  The  De  Chau- 
mont  standard  is  that  of  1  cubic  foot  of  air  per  second  or  3600 
cubic  feet  per  hour,  for  each  person  to  be  accommodated.  De 
Chaumont  assumed  a  condition  of  purity  which  will  permit  less 
than  2  parts  in  10,000  of  C02  over  that  carriecj  by  country  air. 
In  considering  the  same  problem  from  the  basis  of  permissible 
C02,  if  6  parts  of  C02  in  10,000  represents  purity  of  the  required 
air,  then  3000  cubic  feet  per  person  per  hour  is  necessary.  Like- 
wise, the  varying  amounts  for  different  degrees  of  purity  are 

219 


220 


MECHANICS  OF  THE  HOUSEHOLD 


given  by  Kent  in  the  following  table.  The  upper  line  gives  the 
permissible  number  of  parts  of  C02  per  10,000.  while  below  each 
factor  appears  the  number  of  cubic  feet  of  air  required  per  hour 
for  each  person  supplied. 


6 

7 

8 

9 

10 

15 

20 

=  Parts  of  CO2  per  10,000 

3,000 

2,000 

1,500 

1,200 

1,000 

545 

375 

=  Cubic  feet  or  pure  air 

per  hour 

It  is  generally  recognized,  that  it  is  possible  to  live  under 
conditions  where  no  attempt  is  made  to  change  the  air  in  a  build- 
ing. It  is  also  an  established  fact  that  the  only  preventive  and 
cure  for  tuberculosis  is  that  of  living  constantly  in  an  atmosphere 
of  the  purest  air.  The  greatest  attainable  degree  of  health  is 
enjoyed  by  those  who  live  in  the  open  air,  because  oxidation 
is  one  of  the  most  efficient  forms  of  prevention  and  elimin  ation 
of  disease,  and  an  abundance  of  pure  air  is  the  only  assured 
means  of  sufficient  oxidation. 

The  De  Chaumont  standard  is  intended  to  represent  the  limit 
beyond  which  the  sense  of  smell  fails  to  detect  body  odors  or 
" closeness"  in  an  occupied  room.  The  amount  of  C02  that  air 
contains  is  not  an  absolute  index  of  its  purity,  but  it  gives  a 
standard  under  ordinary  conditions,  makes  possible  the  require- 
ment of  a  definite  quantity  of  air.  If  it  were  possible  to  express 
the  amount  of  oxygen  contained  in  the  atmosphere,  the  same 
relative  condition  might  be  attained. 

The  ordinary  man  exhales  0.6  cubic  foot  of  CC>2  per  hour. 
Some  forms  of  lighting  apparatus  produces  this  gas  in  greater 
amounts.  The  ordinary  kerosene  lamp  gives  out  1  cubic  foot  of 
CC>2  per  hour.  A  gas  light  using  5  cubic  feet  of  gas  per  hour 
produces  3.75  cubic  feet  of  C02  in  the  same  time.  Any  form 
of  combustion  permitting  the  products  to  escape  into  the  air 
of  the  room  tends  to  lower  the  quality  of  the  atmosphere  by  add- 
ing to  its'  content  of  C02. 

The  prevailing  impression  that  impure  air  is  heavy  and  settles 
to  the  floor  is  erroneous.  Impurities  in  the  form  of  gases  and 
vapors  (principally  carbonic  acid  gas  and  odors)  diffuse  through- 


VENTILATION  221 

out  the  entire  space,  and  the  entering  fresh  air  tends  to  dilute 
the  entire  volume. 

As  a  quantative  problem,  ventilation  consists  in  admitting 
pure  air  into  an  impure  atmosphere  in  amount  to  give  a  definite 
degree  of  purity.  This  is  accomplished  by  admitting  sufficient 
air  to  completely  change  the  atmosphere  at  stated  intervals,  or 
to  provide  a  definite  quantity  for  each  inhabitant. 

The  methods  by  which  ventilation  may  be  accomplished  will 
depend  on  the  type  of  building  to  be  ventilated  and  the  apparatus 
it  is  possible  to  use.  When  the  use  of  mechanical  ventilation 
appliances  are  permissible,  any  desired  degree  of  atmospheric 
purity  may  be  maintained  at  all  times,  under  any  condition  of 
climate  or  change  of  weather. 

In  buildings  where  mechanical  ventilation  cannot  be  considered 
as  that  of  the  average  dwelling,  the  problem  is  one  of  producing 
an  average  condition  of  reasonably  pure  air  by  natural  convec- 
tion. In  the  average  dwelling,  ventilation  is  accomplished  by 
the  natural  draft  produced  in  chimneys  or  air  flues,  by  partially 
opened  windows  and  by  the  force  produced  by  the  movement  of 
the  outside  air.  In  some  buildings  a  better  condition  of  ventila- 
tion is  attained  by  ordinary  means  than  at  first  sight  seems 
possible. 

The  fact  that  it  is  difficult  to  keep  a  house  at  the  desired  tem- 
perature during  cold  weather  indicates  that  a  considerable 
quantity  of  outside  air  is  constantly  entering  and  heated  air  is 
leaving  the  building.  It  may  be,  however,  that  the  ventila- 
tion under  such  condition  is  unsatisfactory,  even  though  the 
amount  of  air  which  enters  the  building  is  sufficient  in  quantity 
to  produce  a  desirable  atmosphere.  If  the  places  of  entrance 
and  exit  are  so  located  that  the  entering  air  has  no  opportunity 
to  mix  with  the  air  of  the  building,  the  advantage  of  its  presence 
is  lost. 

In  the  burning  of  fuel  in  stov.es  and  furnaces,  the  amount  of 
oxygen  necessary  for  combustion  is  supplied  by  the  air  which  is 
first  taken  into  the  house  and  thus  forms  its  atmosphere  before 
it  can  enter  the  heater.  Theoretically,  about  12  pounds  of  air  are 
required  for  the  combustion  of  a  pound  of  coal,  but  in  practice 
a  much  larger  amount  actually  passes  through  the  heater.  As 
given  by  Suplee,  from  18  to  24  pounds  of  .air  are  actually  used 


222 


MECHANICS  OF  THE  HOUSEHOLD 


in  burning  1  pound  of  coal.  If  20  pounds  of  air  per  pound  of  fuel 
is  taken  as  an  average,  there  will  be  required  198  cubic  feet  of 
air  per  pound  of  coal  consumed.  In  a  building  that  requires  10 
tons  of  coal  to  be  used  during  the  winter  months,  this  would 
necessitate  the  average  use  of  1977  cubic  feet  of  air  per  hour, 
which  must  be  drawn  into  the  house  before  it  can  enter  the  stoves. 
This  air  acts  as  a  means  of  ventilation  and  if  it  is  used  to  advan- 
tage would  furnish  a  supply  sufficient  in  amount  to  produce 
excellent  ventilation,  considerably  more  than  enough  for  two 
people.  The  amount  of  air  drawn  into  the  house  in  this  way  is 
further  increased  by  that  which  passes  into  the  chimney  flue 
through  the  check-draft  dampers,  when  the 
fires  are  burning  low. 

The  aim  of  architects  is  to  construct 
buildings  as  completely  windproof  as  possi- 
ble, but  that  such  construction  is  attained 
in  only  a  slight  degree  is  sometimes  very 
evident  during  cold  weather.  No  matter 
how  tightly  constructed  buildings  may  be, 
most  of  the  contained  air  filters  through  the 
cracks  and  crevices  of  the  walls  or  through 
the  joints  of  the  windows  and  door  frames, 
because  there  is  seldom  any  special  provision 

FIG.  162.— A  simple  ,       .  *        . 

expedient  for  the  Pre-  niade  for   its   entrance.     During  extremely 
yention  of  drafts  and  cold  and  windy  weather  the  amount  of  air 

improving    ventilation.    ,,  ,,        ,  .,  .  , 

that  enters  the  house  in  this  way — because 
of  the  air  pressure  on  the  windward  side — is  sometimes  sufficient 
to  keep  the  temperature  at  an  uncomfortably  low  degree.  Under 
such  conditions,  the  air  drifts  through  the  building  faster  than 
it  can  be  raised  to  the  desired  temperature  and  the  rooms  on  the 
windward  side  of  the  building  cannot  be  kept  comfortably  warm. 
The  common  method  of  ventilation  in  dwellings  is  that  of 
partially  open  windows.  The  air  thus  admitted,  being  colder 
and  consequently  heavier  than  that  at  the  temperature  of  the 
room,  sinks  to  the  lowest  level.  In  so  doing  it  creates  drafts 
that  produce  discomfort  and  act  only  in  the  smallest  degree  to 
produce  the  desired  effect  of  ventilation.  The  effect  of  window 
ventilation  may  be  greatly  improved  by  a  simple  expedient 
illustrated  in  Fig.  162.  In  this,  the  entering  air  meets  a  deflector 


VENTILATION 


223 


in  therform  of  a  board  or  pane  of  glass  that  directs  the  cold  air 
upward  where  it  mingles  with  the  heated  air  with  the  least  pro- 
duction of  a  noticeable  draft.  This  is  the  most  efficient  method 
of  house  ventilating  where  no  special  provision  is  made  for  the 
admission  of  fresh  air. 

The  object  sought  in  ventilating  a  room  is  to  keep  up  the 
quality  of  the  air  by  constant  addition  of  fresh  air,  and  in  order 
to  bring  about  a  uniform  purification  of  the  entire  atmosphere 
the  entering  air  must  be  mixed  with  that  already  in  the  enclosure. 

A  BC 


FIG.   163. — A  chimney  flue  used  as  a  ventilator. 

If  the  discomforts  of  drafts  are  to  be  avoided,  this  mixing  proc- 
ess must  be  brought  about  by  admitting  the  cold  air  at  the 
upper  part  of  the  room. 

Warm  air  rises  to  the  top  of  the  room  because  it  is  lighter  than 
the  colder  air  beneath  it.  The  coldest  air  is  always  lowest  in 
point  of  elevation  and  unless  there  is  some  means  to  stir  up  the 
entire  volume  this  condition  will  always  remain  the  same. 

When  the  easiest  means  of  air  for  entering  and  leaving  are  near 
the  floor,  the  cold  entering  air  and  that  which  goes  out  will 
always  be  in  the  lower  part  of  the  room,  even  when  the  supply 


224 


MECHANICS  OF  THE  HOUSEHOLD 


is  amply  large.  If  no  opportunity  is  given  for  the  fresh  air  to 
mix  with  that  already  in  the  room,  a  poor  average  quality  will 
result. 

In  the  process  of  ventilation,  the  entering  air  should  be  admit- 
ted at,  or  directed  toward,  the  highest  part  of  the  room,  so  that 
the  pure  cold  air  may  have  a  chance  to  mix  with  that  which  is 
warmest.  Air  is  not  a  good  conductor  of  heat,  and  in  mixing 
warm  and  cold  air  the  cold  particles  will  tend  to  float  downward 


FIG. 


164. — Method  of  admitting  cold  air  into  rooms  so  as  to  produce  the  best 
condition  of  ventilation. 


and  take  up  heat  from  the  warmer  air  with  which  it  comes  into 
contact,  and  thus  produces  a  more  uniform  temperature. 

The  condition  most  to  be  desired  is  that  of  admitting  cold 
air  at  a  point  where  it  will  most  readily  mingle  with  the  warm 
air  from  the  source  of  heat.  The  reduction  in  temperature  that 
must  take  place  from  this  mixture  will  produce  a  gravitational 
circulation.  Unfortunately  this  is  not  always  possible  to  attain 
in  an  old  building,  but  in  the  construction  of  a  new  building  air 


VENTILATION  225 

ducts  placed  to  admit  air  at  points  near  the  ceiling  and  located 
with  reference  to  the  supply  of  heat  will  bring  about  the  best 
effect  of  ventilation. 

The  air  which  enters  a  room  should,  therefore,  be  near  the 
top  or  so  directed  that  the  entering  shaft  will  carry  it  upward. 
The  air  which  is  taken  out  of  the  room  should  leave  from  a  point 
near  the  floor.  In  so  doing  it  will  tend  to  produce  a  more  uniform 
quality  and  a  more  even  distributor  of  the  heat. 

In  order  that  the  most  desirable  quality  of  atmosphere  may 
be  attained,  there  should  be  a  constant  supply  of  pure  air  enter- 
ing and  an  equal  amount  discharging  from  the  house.  In  the 
better-constructed  dwelling  such  a  condition  is  often  provided 
through  a  ventilating  flue  that  is  a  part  of  the  chimney.  This 
flue  is  arranged  with  registers  placed  to  take  air  from  the  parts 
of  the  house  requiring  the  greatest  amount  of  air.  Such  an 
arrangement  is  shown  in  the  picture  in  Fig.  163. 

Fig.  164  shows  the  method  of  Fig.  163  combined  with  a 
direct  means  of  admitting  fresh  air  from  the  inside.  The  fresh 
air  ducts  should  be  provided  with  dampers  to  control  the  effect 
of  extreme  cold  and  wind. 

Quantity  of  Air  Discharged  by  a  Flue. — Any  change  of  tem- 
perature of  air  produces  a  change  equal  to  J^91  part  of  its 
volume,  for  each  degree  variation.  If  a  cubic  foot  of  air  is  raised 
in  temperature  1°F.,  its  volume  is  Y±§\  part  larger  than  the 
original  volume,  and  its  buoyancy  in  the  surrounding  air  is 
increased  correspondingly.  Air  that  has  a  temperature  higher 
than  that  surrounding  it  will  tend  to  rise  because  it  is  lighter. 
The  air  rising  from  a  hot-air  register  or  from  a  heated  surface 
are  illustrations  of  this  condition. 

Since  the  change  of  volume — or  what  is  the  same  thing,  its 
tendency  to  rise — increases  ^91  for  each  degree  difference  in 
temperature,  the  upward  velocity  of  highly  heated  air  will  be 
very  great.  In  warm  air  that  fills  a  chimney  flue  or  a  room,  the 
same  tendency  exists,  the  warmest  air  rises  to  the  highest  point 
and  if  the  air  can  escape,  as  in  the  case  of  a  chimney,  a  draft  will 
result. 

The  draft  of  a  chimney,  in  quiet  air,  is  due  to  the  difference  in 
temperature  between  the  air  inside  the  flue  above  that  outside  the 
house.  A  chimney  that  does  not  "draw"  and  causes  a  stove  to 

15 


226  MECHANICS  OF  THE  HOUSEHOLD 

11  smoke,"  will  often  produce  sufficient  draft  after  the  flue 
has  been  warmed.  The  upward  movement  of  the  warmer  air 
in  the  flue  produces  a  constantly  increasing  velocity,  until  it 
reaches  the  top  of  the  chimney.  This  is  an  accelerated  velocity 
that  may  be  calculated  by  use  of  the  formula  given  in  physics, 
to  express  the  velocity  of  accelerated  motion.  The  well-known 
formula  V  =  \/2gh  may  be  modified  to  express  the  conditions 
existing  in  a  flue  and  permit  of  the  calculation  of  the  quantity 
of  air  discharged. 

The  upward  flow  of  air  in  a  chimney  flue  being  due  to  the 
difference  in  temperature  of  the  air  in  the  flue  over  the  outside 
air,  the  flow  of  air  from  the  rooms  will  continue  as  long  as  the 
difference  in  temperature  exists.  Moreover,  the  air  that  is 
discharged  from  the  rooms  will  be  replenished  frpm  the  outside, 
and  for  the  air  sent  out  of  the  flue  a  corresponding  amount  will 
be  brought  into  the  rooms  through  any  openings  that  exist — door 
or  windows  or  through  cracks  or  crevices,  depending  on  the 
completeness  with  which  the  house  is  closed.  In  no  case  is  a 
house  air-tight.  The  air  pressure  registered  by  the  barometer  is 
always  the  same  inside  as  that  outside  the  building.  During 
cold  weather,  when  the  windows  and  doors  are  closed,  the  air  is 
escaping  through  the  chimney  and  also  through  every  little 
crack  and  chink  in  the  top  of  the  rooms  where  the  air  is  warmest. 
The  colder  air  is  entering  at  the  same  time  through  the  joints 
about  windows,  door  casings,  through  the  crevices  in  the  walls 
and  particularly  through  the  open  joints  made  by  the  baseboards 
and  the  floor.  This  latter  entrance  of  cold  air  is  one  of  the  com- 
monest causes  of  cold  floors.  The  shrinkage  of  the  baseboards 
and  floors  from  the  quarter-round  moulding  which  forms  the 
joint  leaves  openings  through  which  cold  air  is  freely  admitted 
from  partitions  and  outside  walls.  The  cold,  heavier  air  remains 
near  the  floor  because  it  can  rise  only  when  heated  or  forced 
upward  by  a  draft.  If  the  same  air  were  permitted  to  enter  at 
points  near  the  ceiling  and  mingle  with  the  warmest  air  in  the 
room,  a  more  uniform  temperature  would  result,  as  well  as 
better  ventilation.  The  entering  cold  air,  mixing  with  the 
warm  air  at  the  top  of  the  room,  would  be  reduced  in  its  tem- 
perature and  weight.  The  heavier  air  in  falling  would  diffuse 


VENTILATION  227 

with  the  air  beneath  it  and  thus  improve  the  general  quality  of 
the  atmosphere. 

It  is  important  to  remember  that  the  discharge  of  air  through 
a  chimney  flue  will  depend,  in  considerable  amount,  on  the  rate 
the  new  air  is  able  to  enter  the  house.  In  a  new,  tightly  con- 
structed house,  the  flue  is  often  capable  of  discharging  air  much 
faster  than  it  can  enter,  when  it  must  find  its  way  in  through 
accidental  openings.  In  such  cases  an  open  door  or  window  im- 
mediately improves  the  draft  of  the  stove. 

The  ventilation  in  the  average  dwelling  is  and  must  be  ac- 
complished by  natural  draft  that  is  generated  through  difference 
in  temperature  of  the  air.  The  possibility  of  providing  an 
acceptable  system  of  continuous  ventilation  is  confined  to  the 
draft  of  the  chimney  or  to  a  flue  provided  especially  for  that 
purpose.  Such  being  the  case,  the  dimensions  of  flues  con- 
structed for  ventilation  should  be  the  subject  of  investigation. 
The  work  that  a  chimney  or  ventilating  flue  has  to  do  is  con- 
tinuous and  will  last  throughout  its  lifetime;  its  proportions 
should  therefore  be  considered  with  more  than  passing  care. 

It  has  been  stated  that  the  method  of  calculating  volumes  of 
air  that  will  pass  through  a  flue  is  based  on  the  formula  used  to 
express  the  velocity  of  accelerated  motion.  The  fundamental 
formula  must  be  changed  to  suit  the  conditions  produced  when 
air  is  heated  and  made  buoyant  by  expansion. 

As  has  been  stated,  the  change  in  temperature  of  air  1°F. 
causes  an  increase  or  decrease  Y±§\  part  of  its  volume  for  each 
degree  change.  Any  portion  of  air,  warmer  than  that  which 
surrounds  it,  tends  to  rise  because  of  its  lighter  weight;  the  tend- 
ency to  rise  increases  with  the  difference  in  temperature.  The 
draft  of  a  flue  is  caused  by  this  condition  of  difference  in  tempera- 
ture between  the  air  inside  the  flue  and  the  outside  atmosphere. 

In  order  that  this  general  condition  may  be  expressed  in  the 
simplest  form  let:  T  =  the  temperature  inside  the  flue  in  de- 
grees F. 

t  =  the  temperature  outside  the  flue  in  degrees  F. 
H  =  the  height  of  the  flue  in  feet. 

T  —  t 
The  quantity  -7qT~  exPresses  the  difference  in  temperature  in 

degrees,  divided  by  the  change  of  volume  for  each  degree.     This 


228  MECHANICS  OF  THE  HOUSEHOLD 

gives  the  constant  upward  tendency  of  the  air  in  passing  through 
the  flue.  If  this  quantity  is  placed  in  the  formula  V  =  \/2gh, 
so  as  to  exert  its  influence  through  the  height  of  flue  H,  the  con- 
dition may  be  expressed: 


The  factor  g,  representing  the  acceleration  of  gravity,  is 
constant  and  equal  to  32  feet  per  second.  The  quantity  2g 
may  be  removed  from  under  the  radical  and  the  formula  becomes : 


V  =  R     / 


The  formula  may  now  be  used  to  express  the  volume  of  dis- 
charge of  air  from  a  flue.  Suppose  such  a  flue  contains  an  area 
of  1  square  foot  in  cross-section  and  that  it  is  desired  to  estimate 
the  air  discharged  from  the  flue  per  hour.  The  value  of  g  is  given 
in  feet  per  second,  and  in  order  to  make  the  formula  express  the 
volume  of  air  discharged  in  cubic  feet  per  hour,  it  must  be 
multiplied  by  the  number  of  seconds  in  an  hour.  Volume 
discharged  in  cubic  feet  per  hour 


=  60  X  60  X  8  H.  =  28,800  ~  H 


This  formula  applies  to  conditions  such  as  will  permit  uniform 
movement  of  the  air  in  a  straight  flue,  uninfluenced  by  irregular, 
odd-shaped  passages  and  rough  surfaces.  Moreover,  it  is 
supposed  that  the  air  may  enter  the  house  as  rapidly  as  it  escapes. 
The  theoretical  discharge  will,  in  most  instances,  be  less  than  the 
calculated  amount,  because  the  air  cannot  enter  the  house  as 
fast  as  it  may  be  discharged  by  the  flue.  It  is  a  common  custom 
to  consider  the  theoretical  flue  only  50  per  cent,  efficient.  As 
applied  to  the  formula,  the  constant  28,800  when  reduced  50  per 
cent,  will  become  14,400,  and  will  be  so  used  in  the  calculations 
as  follows. 

As  an  illustration  of  the  application  of  the  formula,  suppose 
that  the  temperature  in  the  house  and  in  the  flue  is  70°F.  and  that 
the  outside  temperature  is  20°F.  The  height  of  the  chimney  is 
30  feet.  The  area  of  the  flue  is  1  square  foot.  Volume  =  14,400 


VENTILATION 


229 


T-t 
491 


H  =  14,400 


70  -  20 
491™  x  30  =  25,140  cubic  feet  per  hour. 


Such  a  ventilating  flue  would  be  sufficient  in  size,  under  the 
conditions  given,  to  furnish  air  at  the  rate  of  25,140  cubic  feet 
per  hour  or  30  cubic  feet  per  minute  to  13  persons,  provided  of 
course  that  the  air  could  enter  the  building  at  the  rate  demanded. 
Where  no  provision  is  made  for  the  air  to  enter  the  building 
it  must  find  its  way  by  the  accidental  openings.  A  common 
illustration  of  this  effect  may  be  noticed  in  the  rate  at  which  the 
fire  of  a  stove  will  burn  in  a  tightly  closed  room.  The  opening 
of  a  door  or  window  causes  an  immediate  increase  of  combustion, 
because  of  the  extra  air  supply.  It  is  evident  that  in  well- 
constructed  houses  other  means  should  be  provided  for  admitting 
air  than  that  of  accidental  opening. 

The  following  table  calculated  by  the  above  formula  gives  the 
quantity  of  air  in  cubic  feet  per  hour  discharged  through  a  flue 
of  1  square  foot  cross-section.  The  table  shows  the  calculated 
discharge  from  flues  of  heights  varying  from  15  to  40  feet,  and 
with  temperature  differences  from  10°  to  100°  between  the  out- 
side air  and  that  of  the  house. 


Height  of  flue 
in  feet 

Temperature  of  air  in  the  flue  above  that  of  external  air 

10 

15 

20 

25 

30 

50 

100 

15 

7,980 

9,720 
11,180 

11,280 
13,080 

12,550 
14,520 

13,800 
15,900 

17,820 
20,520 
22,980 

25,140 
29,040 

20 

9,180 

25 

10,260 

12,600 

14,520 

16,260 
17,825 
19,200 

17,820 

32,460 

30 

11,280 
12,180 

13,800 
14,880 
15,900 

15,900 

19,500 
21,060 

25,140 

35,580 

35 

17,160 

27,180 

38,400 
40,980 

40 

13,020 

18,360 

20,520 

22,500 

29,040 

In  Fig.  163  is  illustrated  the  form  of  chimney  that  is  often  used 
for  the  ventilation  of  dwellings.  This  is  built  with  three  flues. 
The  flue  to  the  left — marked  A  at  the  top— is  intended  to  carry 
away  the  smoke  and  gases  from  the  kitchen  range.  The  flue 


230  MECHANICS  OF  THE  HOUSEHOLD     ' 

to  the  right  is  that  to  which  is  connected  the  smoke  pipe  from  the 
furnace.  The  flue  in  the  middle  marked  B  is  for  ventilation. 
Occupying  as  it  does  the  space  between  the  other  two,  it  is  kept 
warm  by  the  heat  of  the  other  flues  and  the  draft  is  thus  increased. 
Openings  to  the  flue  are  shown  in  the  different  floors  at  the  points 
R  and  S.  The  openings  are  furnished  with  registers  which  may 
be  regulated  to  suit  the  weather  conditions. 

The  dimensions  of  such  a  flue  may  be  calculated  by  the  formula 
given  or  the  area  may  be  taken  from  the  table  to  correspond 
with  required  conditions.  In  all  cases  flues  should  be  made 
ample  in  size,  as  they  must  often  do  their  maximum  work  under 
the  poorest  conditions  for  the  production  of  good  draft. 

The  amount  of  air  discharged  from  the  flue  as  given  in  the 
table  is  due  to  the  gravitational  effect  alone.  The  suction 
produced  by  the  wind  adds  in  a  very  large  degree  to  the  amount 
of  air  discharged.  The  quantity  of  air  that  will  flow  from  a 
30-foot  flue,  by  reason  of  the  suction  of  the  wind,  blowing  7  miles 
per  hour  is  equal  to  the  same  flue  working  by  gravity  with  a 
temperature  difference  of  20°.  With  a  wind  velocity  of  7  miles 
per  hour  and  a  temperature  as  given,  the  capacity  of  the  flue  is 
doubled.  It  is  easy,  therefore,  to  understand  why  the  rate  at 
which  fires  burn  is  so  greatly  increased  by  high  winds.  At  the 
time  of  very  high  winds,  a  chimney  flue  will  carry  away  three 
and  even  four  times  the  volume  discharged  at  the  time  of  atmos- 
pheric calm. 

Cost  of  Ventilation. — The  cost  of  good  ventilation  is  often 
looked  upon  as  prohibitive,  because  of  the  expense  in  heat  neces- 
sary to  keep  the  inside  atmosphere  at  standard  purity.  Cost  of 
ventilation  is  determined  by  analysis  of  the  known  conditions  and 
calculations  made  of  the  amount  of  extra  heat  necessary  to 
warm  the  greater  volume  of  air. 

The  common  practice  of  estimating  the  quantity  of  heat  used 
in  any  form  of  heating  or  ventilation  is  by  reference  to  the  B.t.u. 
used  in  producing  the  desired  condition.  This  unit,  as  has  al- 
ready been  stated,  is  the  amount  of  heat  necessary  to  change  a 
pound  of  waterj  1°F. 

In  considering  the  cost  of  heating  the  air  for  ventilation,  it 
must  be  borne  in  mind  that  the  heat  used  in  raising  the  tempera- 
ture of  the  air  contained  in  an  enclosure  is  only  a  part  of  that 


VENTILATION  231 

necessary  for  warming  the  building.  Most  of  the  heat  used  goes 
to  keep  up  the  loss  due  to  radiation  and  conduction  which  goes 
on  from  the  windows,  the  walls  and  other  parts  of  the  building 
that  are  exposed  to  the  outside  cold.  The  material  of  which 
the  building  is  composed  must  be  heated  and  in  turn  radiates 
its  heat  to  the  colder  outside  air. 

The  quantity  of  heat  necessary  to  change  the  temperature  of 
a  definite  amount  of  air  is  easy»of  calculation.  The  problem 
is  that  of  determining  the  number  of  heat  units  required  to 
warm  the  necessary  air  to  suit  the  average  condition  of  weather. 
We  will  assume  that  the  house  is  heated  to  the  normal  tempera- 
ture 70°,  and  that  the  additional  cost  of  heating  the  air  for  ven- 
tilation over  the  amount  thus  expended  is  the  cost  of  ventilation. 

Assuming  that  the  house  is  so  constructed  that  it  is  possible 
to  supply  air  at  the  rate  of  1000  cubic  feet  per  hour  to  each 
person  of  a  family  of  five,  this  condition  will  necessitate  5000 
cubic  feet  of  air  per  hour  or  120,000  cubic  feet  of  air  per  day. 

The  house  is  such  that  10  tons  of  coal  are  required  per  year, 
at  a  cost  of  $10  per  ton.  The  period  of  winter  weather  will  be 
considered  5  months  of  30  days  each.  This  will  be  150  days, 
during  which  the  fuel  for  heating  the  house  will  cost  66%  cents 
per  day. 

The  average  temperature  of  the  outdoor  air  during  the  entire 
period  will  be  assumed  to  be  20°F.,  thus  requiring  the  air  for 
ventilation  to  be  changed  50°  in  order  to  raise  it  to  the  normal 
temperature,  70°. 

The  weight  of  a  cubic  foot  of  air  at  70°  is  practically  0.075 
pound.  The  120,000  cubic  feet  of  air  used  per  day  will,  therefore, 
weigh  0.075  X  120,000  =  9000  pounds  which  must  be  raised 
50°  in  temperature. 

In  order  to  express  in  B.t.u.  the  necessary  heat  required  to 
produce  the  change  of  air  temperature,  the  quantity  of  air  is 
best  stated  in  an  equivalent  amount  of  water.  The  specific 
heat  of  air  is  0.237;  that  is,  the  amount  of  heat  necessary  to 
change  a  pound  of  air  1°  is  0.237  of  the  amount  used  in  changing 
1  pound  of  water  1°.  The  9000  pounds  of  air  expressed  as  an 
equivalent  amount  of  water  will  then  be: 

9000  X  0.237  =  2133  pounds  of  water. 


232  MECHANICS  OF  THE  HOUSEHOLD 

This  amount  of  water  raised  1°  is  equivalent  to  raising  120,000 
cubic  feet  of  air  1°.  Now  the  average  change  in  the  temperature 
of  the  air  is  50°,  so  that  50  X  2133  will  be  the  number  of  heat 
units  used. 

50   X  2133   =   106,650  B.t.u. 

'That  is,  106,650  B.t.u.  will  be  required  to  heat  the  air  for 
ventilation  one  day. 

In  order  to  express  this  amount  of  heat  in  terms  of  fuel  con- 
sumed, it  will  be  assumed  that  the  coal  contained  14,000  B.t.u. 
per  pound,  this  being  a  fair  valuation  of  good  coal.  The  average 
house-heating  furnace  will  turn  into  available  heat  about  50 
per  cent,  of  the  fuel  burned.  This  value  is  taken  from  house- 
heating  fuel  tests  made  at  the  Iowa  State  College.  The  avail- 
able heat  in  each  pound  of  coal  then  will  be  7000  B.t.u. 

106,650  -f-  7000  =  15.2  pounds  of  coal. 

That  is,  15.2  pounds  of  coal  per  day  must  be  burned  in  order 
to  furnish  1000  cubic  feet  of  air  per  person  each  hour  at  the 
desired  temperature. 

At  $10  a  ton  of  2000  pounds,  the  fuel  costs  %  cent  per  pound. 
The  cost  of  ventilation  is,  therefore,  %  X15.2  =  7.60  cents  a 
day,  not  an  extravagant  amount  for  good  air. 

It  is  evident  that  with  the  use  of  hot-air  furnaces  which  take 
their  entire  amount  of  air  from  outdoors,  the  extra  amount  of 
heat  necessary  for  this  improved  quality  of  atmosphere  is  very 
well  expended.  The  use  of  ventilating  devices  adds  only  a 
relatively  small  amount  to  the  total  cost  of  heating  and  provides 
for  the  well-being  of  the  occupants  of  the  house — in  the  form  of 
good  air — an  amount  of  healthfulness  impossible  of  calculation. 

The  best  ventilation  is  attained  where  a  constant  supply  of 
fresh  air  is  admitted  to  the  house  at  points  from  which  the  best 
circulation  may  be  secured  and  equal  quantities  of  vitiated  air 
are  removed  from  the  different  apartments. 

It  is  understood  that  in  the  process  of  natural  ventilation  the 
desired  condition  can  only  be  approximated  and  that  the  per- 
missible ventilation  appliances  are  so  placed  as  to  give  results 
such  as  to  permit  the  air  to  follow  the  natural  laws  that  must 
prevail. 


VENTILATION 


233 


If  the  house  is  heated  by  stoves,  the  outside  air  is  best  admitted 
near  the  ceiling,  so  that  the  cold  air  on  entering  may  come  into 
contact  and  mingle  with  the  warmest  air  in  the  room.  The 
circulation  will  by  this  method  be  effected  by  gravity. 

In  the  use  of  the  hot-air  furnace,  the  air  supply — as  has  already 
been  explained  in  the  .figures  on  pages  55  and  58 — is  brought 
from  the  outside,  where  after  being  heated  it  enters  the  rooms 
through  the  registers  placed  near  the  floor.  Being 
warmer  than  the  air  in  the  room,  it  tends  to 
quickly  rise.  The  currents  set  up  by  its  motion 
help  to  produce  a  uniform  temperature  and  to 
diffuse  the  new  air  through  the  entire  space.  The 
more  evenly  the  air  is  distributed  the  more  uni- 
form will  be  the  condition  of  temperature  of  the 
room. 

In  hot-water  and  steam  heating,  the  direct 
method  of  heating  in  Fig.  29  and  the  indirect 
method  of  Fig.  30  show  two  forms  of  apparatus 
for  admitting  air  to  buildings  that  are  quite  gener- 
ally employed  for  ventilation  of  dwellings.  In  the 
use  of  all  such  devices  for  ventilation  purposes, 
there  should  be  provided  means  of  escape  of  air 
corresponding  in  amount  to  the  fresh  air  admitted. 
The  exhaust  air  vent  should  be  located  near  the 
floor  to  bring  about  the  best  results.  The  degree 
of  success  attending  the  use  of  such  apparatus 
will  depend  on  the  amount  of  care  taken,  to  suit 
the  position  of  the  dampers  to  the  prevailing  tester;  anTnstru- 
weather.  ment. used  to  de- 

.  .      _,  rrn  . ,          /.      •     •      termine  the  qual- 

The  Wolpert  Air  Tester. — The  purity  of  air  is  ity  of  air 
expressed  by  quantity  of  carbonic  acid  gas  in- 
cluded in  its  composition.     In  order  to  determine  the  degree  of 
purity  of  any  atmosphere  the  amount  of  contained  gas  must  be  de- 
termined.    This  is  accomplished  by  use  of  simple  apparatus  that 
may  be  successfully  operated  by  those  who  are  unacquainted 
with    chemical   analytical   methgds.     The    process    is   due   to 
chemical  action  but  the  manipulation   of  the  required  appa- 
ratus is  purely  mechanical. 

Fig.  165  shows  the  Wolpert  air  tester  which  is  a  form  of  this 


FIG.  165.— 


234 


MECHANICS  OF  THE  HOUSEHOLD 


apparatus  that  has  given  general  satisfaction.  The  results 
attained  by  its  use  are  approximate  but  sufficiently  exact  for 
all  practical  purposes.  The  apparatus  consists  of  a  graduated 
glass  tube  in  which  fits  a  rubber  piston  mounted  on  a  hollow 
glass  rod,  through  which  the  sample  of  air  is  admitted  to  the  tube. 
The  chemicals  used  for  absorbing  the  carbonic  acid  gas  are  fur- 
nished with  the  instrument  but  may  be  replenished  without 
difficulty.  Directions  for  its  use  are  furnished  with  the  tester 
that  may  be  readily  followed  after  a  trial.  The  results  ob- 
tained are  read  directly  from  the  side  of  the  tube.  The  tester  may 
be  obtained  from  any  dealer  in  chemical  or  physical  apparatus. 
Pneumatic  Temperature  Regulation. — Pneumatic  temperature 
regulation  is  very  generally  used  in  large  and  complicated  heating 


FIG.   166. — Thermostat  regulator  and  motor-valve  attached  to  a  radiator. 

systems,  because  of  its  positive  action  and  completeness  of  heat 
control.  This  method  of  heat  regulation  utilizes  the  energy  of 
compressed  air,  with  which  to  open  and  close  the  valves  of  the 
radiators.  It  may  be  adapted  to  any  mode  of  heating  and  can 
be  used  with  any  size  of  plant,  but  is  particularly  suited  to  ex- 
tended systems.  The  radiators,  providing  heat  for  any  par- 
ticular space,  are  under  control  of  separate  thermostats, 
which  by  means  of  motor  valves  admit  heat  only  as  required. 
A  motor,  operated  by  compressed  air,  is  attached  directly  to 


VENTILATION 


235 


each  radiator  valve.  Any  change  in  temperature  of  the  room 
causes  the  thermostat  to  correct  in  the  radiator  the  required 
amount  of  heat. 

With  this  method  of  regulation  the  temperature-controlling 
element  of  the  thermostat,  like  that  of  the  electro-thermostatic 
system,  is  a  sensitive  part,  which  by  expanding  and  contracting 
with  the  heat  and  cold  directly  controls  the  heat  in  any  part  of 
the  building.  The  motive  power  for  opening  and  closing  the 
valves  of  steam  or  hot-water  radiators  or  for  operating  the  dampers 
in  a  hot-air  system  is  supplied  by  compressed  air.  The  air  supply 
is  furnished  by  an  air  compressor  which  auto- 
matically stores  air  under  pressure  in  a  pressure 
tank,  from  which  is  drawn  the  necessary  energy, 
as  occasion  demands.  The  air  is  conducted  to 
the  motors  through  small  pipes  which  are  con- 
nected with  the  regulating  elements  and  also  with 
the  motors.  The  function  of  the  thermostat  is  to 
so  govern  the  air  which  enters  the  motor  as  to 
correct  any  change  in  the  temperature  of  the 
rooms.  This  it  does  by  opening  and  closing  the 
valves  as  occasion  demands. 

In  Fig.  166  is  shown  the  arrangement  of  the 
thermostat  T  as  it  appears  on  the  wall.  Air 
from  the  supply  tank  is  conveyed  by  the  pipe  A 


/nnnn\ 


w 

FIG.    167.— 

through  the  thermostat  T  to  the  motor  valve  V  at-  Outside  view  of 

f    J.T-      thermostat  as  it 

tached    to    the   radiator.     The   function   ot   the  appears  in  use. 
thermostat  is  that  of  so  controlling  the  radiator 
valve  by  means  of  the  motor  V  that  the  radiator  will  give  out 
just  sufficient  heat  to  keep  the  room  at  the  desired  temperature. 
A  closer  view  of  the  thermostat  is  given  in  Fig.  167. 

The  thermostat  illustrated  in  Fig.  167  is  that  employed  by 
the  National  Regulator  Co.  The  drawing  shows  the  exterior 
and  interior  construction  of  the  parts  enclosed  in  the  previous 
illustration.  The  pipe  C  at  the  right  and  opening  P  at  the 
left  are  the  same  as  A  in  Fig.  169;  likewise,  the  pipe  D  connects 
at  the  opening  M  of  the  motor  valve  in  Fig.  169. 

Referring  again  to  Fig.  168,  the  sensitive  part  consists  of  a 
tube  A  of  vulcanized  rubber.  It  is  the  dark-shaded  part  in  the 
left-hand  drawing.  Any  change  in  the  air  temperature  influ- 


236 


MECHANICS  OF  THE  HOUSEHOLD 


ences  the  length  of  this  tube.  The  changing  length  of  the  tube 
effects  the  air  supply  to  close  the  radiator  valve  when  the  tem- 
perature rises  above  the  desired  amount  and  to  reopen  it  when 
more  heat  is  required.  A  finely  threaded  screw  passes  through 
the  plug  H  at  the  top  and  to  this  is  secured  the  indicating  disc 
X.  The  bottom  of  this  screw  is  cupped  to  receive  the  point  of 
the  rod  K,  which  connects  with  the  piece  L.  Any  change  in 
length  of  the  sensitive  tube  moves  the  valve  lever  0}  and  thus 
opens  or  closes  the  air  port  G. 

Air  under  pressure  is  supplied  by  the  pipe  C,  connected  to 
the  air  supply,  flowing  into  the  thermostat  through  the  filter 

P,  the  restriction  S,  the  passage  T,  and 
the  port  G.  The  adjustment  of  the 
thermostat  for  different  temperatures 
is  provided  for  by  the  screw  J  through 
the  top  plug  H,  and  the  indicating  disc 
-X".  The  screw  R  in  the  connector  Q  at 
the  base  of  the  thermostat  is  a  needle 
valve  which  opens  or  closes  the  connec- 
tion with  the  air  supply,  and  is  used  as 
an  air  shut-off  valve  when  it  is  desired 
to  remove  the  thermostat.  The  screw 
S  is  a  restriction  valve  which  controls 
the  supply  of  air  to  the  thermostat, 
and  this  screw  is  set  so  as  to  allow  the 
air  to  pass  in  a  restricted  quantity. 

FIG.  168.— Internal  con-        When  the  temperature  of  the  apart- 
struction  of  the  National    ment  has   risen    so    as   to  expand  the 

Regulator     Co.'s     thermo-     , ,  , .       ,  4,1 

static  regulator.  thermostatic  element  A,  the  pressure  on 

K  and  L  is  relieved  and  the  spring  N 

closes  the  port  G.  The  air  admitted  through  the  restriction 
screw  S,  since  it  cannot  escape  through  the  port  G}  accumu- 
lates in  the  passage  Y  and  pipe  D,  filling  the  diaphragm  and 
moving  the  valve  into  the  position  to  decrease  the  supply  of 
heat.  When  the  temperature  of  the  apartment  has  decreased 
so  as  to  produce  pressure  on  the  connecting  rod  K,  through 
the  contraction  of  the  thermostatic  element  A,  the  port  G  will 
be  opened  by  the  valve  lever  0,  allowing  the  air  in  the  pipe  D, 
together  with  that  which  flows  through  the  restriction  S,  to 


VENTILATION 


237 


escape  through  the  passage  W  to  the  atmosphere,  allowing  no 
air  to  accumulate  in  the  pipe  D,  and  thus  permitting  the  spring 
at  the  diaphragm  to  actuate  the  damper  or  valve  for  more  heat. 
The  amount  of  air  released  through  the  port  G  by  the  valve 
lever  0  varies  the  pressure  accumulated  in  the  pipe  D  and  pro- 
duces the  graduated  or  intermediate  action  desired. 

A  further  application  of  air  pressure  in  temperature  regulation 
is  that  of  the  type  of  motor  shown  in  Fig.  170.  This  device  is 
intended  to  open  and  close  dampers  such  as  are  used  in  the  auto- 
matic regulation  of  temperature  where  heated  air  is  used  to  warm 
the  buildings.  The  operation  of  the  motor  is  the  same  as  that 
which  controls  the  steam  valve.  The  pressure  exerted  by  the 
diaphragm  is  applied  at  A  and  the  attachment  to  the  damper  is 


FIG.  169. — Cross-section  of 
pneumatic  radiator  valve  show- 
ing its  internal  construction. 


FIG.   170. — Pneumatic  motor  valve  for 
automatic  control  of  dampers,  etc. 


made  at  B.     The  motors  indicated  at  V  and  N  in  Fig.  174  and 
D  in  Fig.  175  are  examples  of  its  application. 

Mechanical  Ventilation. — Draft  ventilation  produced  by  open 
windows,  flues  and  chimneys  is  influenced  by  extremes  of  tem- 
perature and  by  the  force  and  changing  direction  of  the  wind; 
it  is,  therefore,  but  imperfectly  controlled.  The  superiority  of 
mechanical  ventilation  is  generally  recognized  because  the 
amount  of  entering  air  may  be  regulated  to  suit  any  circum- 
stance and  its  temperature  and  humidity  varied  to  conform  to 
any  desired  atmospheric  conditions.  Mechanical  ventilating 
plants. are  seldom  employed  in  any  but  the  more  pretentious 
dwellings,  but  their  use  has  extended  to  a  degree  that  they  are 
occasionally  installed  in  apartment  buildings  and  their  further 


238 


MECHANICS  OF  THE  HOUSEHOLD 


application  is  likely  to  grow.  Neither  the  cost  of  installation 
nor  the  expense  of  operation  is  prohibitive  in  dwellings  of  the 
better  types.  Mechanical  ventilation  is  quite  generally  employed 
in  school  buildings,  auditoriums,  hospitals,  public  buildings  and 
others  where  means  will  permit,  and  there  is  a  universal  recogni- 
tion of  the  effects  of  the  agreeably  conditioned  air. 

Mechanical  ventilation  may  be  accomplished  by  power-driven 
fans,  either  by  exhausting  the  air  from  the  building  or  by  forcing 
air  into  it,  and  under  some  conditions  a  combination  of  the  two 
methods  is  used. 


FIG.     171. — Exhaust   fan   for 
induced  ventilation. 


FIG.    172. — Ventilation  apparatus  in  which  is 
included  the  heater  coils,  the  fan  and  the  motor. 


The  exhaust  method  of  ventilation  is  that  in  which  air  is  blown 
out  of  the  building  by  a  fan;  and  the  supply,  to  replenish  that 
taken  away,  is  conducted  into  the  building  through  ducts  pre- 
pared for  the  purpose.  In  some  cases  the  induced  air  supply 
leaks  into  the  rooms  through  the  joints  in  the  doors  and  windows, 
and  through  the  accidental  crevices.  In  Fig.  171  is  shown  a 
simple  exhaust  fan  installed  to  produce  such  a  change  of  air. 
It  is  suitable  for  kitchens  and  other  places  where  it  is  desired  to 
eliminate  smoke  or  gases  rather  than  to  pr.oduce  a  supply  of  air. 
With  this  apparatus  the  air  of  the  room  is  blown  out  by  the  rotat- 
ing fan  and  new  air  to  take  the  place  of  that  exhausted  is  drawn 
in  at  any  convenient  opening. 


VENTILATION  239 

The  Plenum  Method. — That  form  of  mechanical  ventilation 
by  means  of  which  air  is  forced  into  the  rooms  is  known  as  the 
plenum  method.  It  is  the  most  positive  means  of  air  supply 
because  its  action  is  attended  by  a  slight  pressure  above  the 
outside  air;  it  is  continuous  in  action  and  the  amount  of  enter- 
ing air  is  under  control.  The  escape  of  the  expelled  air  is  made 
through  vent  flues  especially  constructed  for  the  purpose. 

Ventilation  Apparatus. — Fig.  172  illustrates  the  form  of  appara- 
tus used  for  ventilating  buildings  where  no  attempt  is  made  at 
washing  or  humidifying  the  air.  Enclosed  in  a  sheet-iron  case 
C  is  a  fan  which  is  driven  by  the  electric  motor  M .  The  capacity 
of  the  fan,  for  the  delivery  of  air,  is  made  to  suit  the  require- 
ments of  the  building.  In  this  case  the  fan  is  secured  to  an 
extension  of  the  armature  shaft  of  the  motor.  Connecting  with 
the  case  which  encloses  the  fan  is  another  sheet-iron  box  H, 
containg  coils  of  heating  pipe.  The  heating  apparatus  is  designed 
to  change  the  temperature  of  the  entering  air  to  suit  the  require- 
ments of  the  building. 

This  jepresents  the  draw-through  or  induced-draft  type  of 
ventilation  apparatus.  The  air  delivered  by  the  fan  induces  a 
flow  of  outside  air  which  is  drawn  through  the  heating  coils  and 
discharged  through  the  opening  E.  At  this  point  it  enters  the 
main  ventilation  duct  from  which  it  is  distributed  by  branch 
conduits  throughout  the  building. 

The  temperature  of  the  air  sent  out  from  the  fan  is  regulated 
by  the  steam  valves  of  the  heater  coils  to  suit  the  prevailing 
conditions.  Under  some  installations  of  this  character  the  venti- 
lating air  is  made  to  furnish  the  heat  necessary  to  warm  the 
building  as  well  as  to  provide  its  air  supply.  As  ordinarily 
used,  however,  the  temperature  of  the  ventilating  air  is  the 
same  as  that  of  the  room. 

The  method  of  conveying  air  to  the  various  apartments 
depends  entirely  on  local  conditions.  The  conduits  may  be 
made  of  sheet  iron,  placed  to  suit  the  existing  conditions;  but 
when  a  building  is  constructed  with  a  ventilating  plant  in  view 
as  a  part  of  the  building  equipment,  it  is  customary  to  make  the 
ducts  part  of  the  partitions.  In  brick  buildings  the  ducts  are 
constructed,  so  far  as  it  is  practicable,  in  the  walls.  These 
ducts  are  made  in  size  and  arrangement  to  suit  the  amount  of 


240  MECHANICS  OF  THE  HOUSEHOLD 

air  required  for  each  room.  When  the  plant  is  put  into  operation 
each  duct  is  tested  with  an  anemometer  which  indicates  the 
velocity  of  the  entering  air.  The  calculated  amount  of  air,  deter- 
mined by  the  velocity  and  area  of  the  entering  column,  when 
compared  with  the  necessary  quantity  demanded  for  good 
ventilation,  gives  the  efficiency  of  the  system. 

Air  Conditioning. — In  addition  to  the  possibility  of  a  constant 
supply  of  air,  a  combination  of  the  exhaust  and  plenum  methods 
admits  of  air  purification.  With  such  a  plant,  the  air  may  be 
washed  free  from  all  suspended  dust  or  gases  and  moistened  to 
any  degree  of  humidity.  The  process  of  washing  and  humidi- 
fying air  is  known  as  air  conditioning.  Apparatus  for  air  condi- 
tioning is  made  in  a  variety  of  forms  to  produce  any  desired 
extent  of  air  purification  and  any  degree  of  humidity.  The 
plant  may  be  regulated  by  hand  or  it  may  be  made  entirely 
automatic  in  its  action.  Air-conditioning  plants  may  be  arranged 
to  produce  air  that  is  purified,  humidified  and  warmed  during 
winter  weather  and  in  summer  the  hot  humid  atmosphere  may  be 
cooled  and  dehumidified  to  a  temperature  and  percentage  of 
moisture  that  is  most  agreeable. 

Conditioned  air  is  often  used  in  manufactories,  not  for  the 
purpose  of  supplying  good  air  to  the  employees  but  because  of 
the  effect  of  the  atmospheric  air  on  the  products.  The  manufac- 
ture of  textile  fabrics  often  demands  a  constant  atmospheric 
humidity  in  order  that  the  material  produced  may  be  uniform 
in  grade;  this  is  particularly  true  in  the  making  of  silks.  Vari- 
ous manufactories  require  an  atmosphere  free  from  lint  and 
dust  in  order  that  the  best  quality  of  material  may  be  produced. 
The  air  for  ventilation  in  such  places  is  washed  free  from  all 
suspended  matter  before  being  sent  into  the  building. 

In  Fig.  173  is  indicated  an  application  of  apparatus  similar 
in  construction  to  that  just  described.  The  arrangement  of 
the  parts  is  such  as  to  produce  a  Plenum  hot-air  system  of  venti- 
lation and  temperature  regulation. 

The  plant  occupies  a  room  in  the  basement  and  the  drawing 
shows  the  method  of  heating,  together  with  the  plan  of  distribu- 
tion. The  air  duct  leading  to  the  room  above  furnishes  an 
example  of  the  manner  of  admitting  the  warmed  air  to  the  rooms. 
The  dampers  Ci,  Cz,  etc.,  are  controlled  by  separate  motors. 


VENTILATION 


241 


The  motor  M  is  under  the  control  of  the  thermostat  T  in  the 
room  above.  Any  change  of  temperature  in  the  room  is  cor- 
rected by  the  damper  to  admit  cold  or  warm  air  as  is  desired. 

The  power-driven  fan  F  draws  in  outdoor  air  from  an  opening 
A,  through  a  set  of  heater  coils  HI,  in  which  it  is  raised  consider- 
ably in  temperature.  The  heater  in  this  case  is  a  coil  of  steam 
pipes.  The  air — after  being  warmed — is  taken  into  the  fan  and 
from  it  may  be  sent  through  a  second  set  of  coils  H2)  to  receive 
additional  heat,  or  if  already  sufficiently  warmed  the  air  from 
the  fan  may  pass  under  the  second  set  of  coils  and  receive  no 
heat  from  them.  Under  the  first  heater  coil  is  also  a  bypass 


FIG.   173.— Plenum  hot-blast  heating  system  with  temperature  regulation. 

which  may  be  opened  by  the  motor  N  to  admit  cold  air  that  is 
drawn  directly  into  the  fan.  The  movement  of  the  air  through 
these  bypasses  is  under  control  of  the  thermostat,  which  causes 
the  motor  N  to  open  or  close  the  bypass  to  suit  the  temperature 
of  the  room.  When  the  bypass  is  opened  the  steam  is.  shut 
off  from  the  heater  coils. 

Examination  of  the  drawing  will  show  that  the  air  from  the 
fan  may  pass  through  a  second  heater  H2,  to  the  place  marked 
warm  air,  or  it  may  pass  under  the  heater  to  the  compartment 
marked  cold  air.  The  amount  of  warm  and  cold  air  which  enters 
the  duct  is  regulated  by  the  position  of  the  dampers  C. 

16 


242  MECHANICS  OF  THE  HOUSEHOLD 

The  position  of  the  dampers  C,  which  is  controlled  by  the 
motors  M,  is  made  to  take  amounts  of  cold  or  warm  air  to  pro- 
duce the  desired  temperature  in  the  rooms.  The  motors  Ci, 
etc.,  are  under  control  of  the  thermostat  in  each  room.  Any 
change  of  temperature  in  the  room  will  immediately  affect  the 
thermostat.  The  effect  on  the  thermostat  will  so  change  the 
air  pressure  in  the  motor  that  the  valve  C  is  moved  to  correct 
the  difference  in  room  temperature.  If  warm  air  is  demanded, 
the  motor  changes  the  damper  C  to  close  the  cold-air  supply  and 
take  air  that  must  pass  through  the  heater  coils  H2.  If  only 
cold  air  is  desired  the  damper  will  turn  to  shut  off  the  course 
through  the  heaters  and  admit  air  directly  from  outdoors. 

Humidifying  Plants. — Mechanical  ventilation  plants  that  are 
intended  for  washing  the  air  may  be  made  up  of  parts  similar  to 
that  of  Fig.  173,  but  in  addition  to  the  apparatus  shown  provision 
is  made  for  the  air  to  pass  through  a  chamber  filled  with  a  spray 
of  water.  The  air  in  passing  through  this  spray  is  washed  free 
of  dust  and  at  the  same  time  absorbs  water  necessary  for  its 
desired  humidity. 

The  humidity  of  air  may  be  increased  by  the  addition  of  mois- 
ture or  decreased  (dehumidified)  by  raising  its  temperature,  there- 
by increasing  its  capacity  for  containing  moisture.  Suppose  that 
air  at  50°  is  saturated  with  moisture;  it  will  contain  practically 
4  grains  of  water  per  cubic  foot.  If  now  the  temperature  of  the 
air  is  raised  to  70°,  the  same  amount  of  air  is  capable  of  contain- 
ing 8  grains  of  water  and  is,  therefore,  only  50  per  cent,  saturated. 

Humidification  is  accomplished  in  air-conditioning  plants 
through  one  of  two  general  methods:  by  the  evaporation  type  of 
apparatus,  in  which  the  passing  air  absorbs  moisture  from  con- 
tact with  a  large  area  of  water;  or  the  spray  method,  in  which 
the  water  is  broken  into  a  very  fine  spray  by  a  specially  devised 
nozzle  and  thus  rendered  easy  of  absorption  by  the  air  to  be 
moistened.  A  third  method  is  sometimes  employed,  in  which 
steam  is  introduced  into  the  air  supply.  Steam  is  already  vapor- 
ized water  and  immediately  becomes  a  part  of  the  air  without 
further  change.  The  steam  type  of  humidifying  plant  possesses 
features  that  limit  its  application,  in  that  the  steam  in  some  cases 
may  possess  objectionable  odor  or  includes  the  vapor  of  grease, 
either  of  which  would  materially  effect  its  use.  Further,  the 


VENTILATION  243 

heat  of  vaporization  liberated  by  the  condensing  steam  is  also 
a  factor  that  influences  the  temperature  of  the  air  and  in  case 
of  direct  humidification  must  receive  special  attention. 

Vaporization  as  a  Cooling  Agent.— The  evaporation  of  water 
has  a  distinct  value  aside  from  humidifying  the  air,  in  that 
the  cooling  effect  is  in  direct  proportion  to  the  added  moisture. 
In  the  process  of  evaporation  the  heat  necessary  to  change  the 
water  into  vapor  is  taken  from  the  surrounding  air  and  the  tem- 
perature is  thus  materially  lowered. 

In  practical  air-conditioning  apparatus,  of  the  evaporative  or 
spray  types,  the  process  consists  of  drawing  the  outside  air  into 
a  chamber  filled  with  falling  water  that  is  broken  up  into  drops 
like  rain  or  spray.  In  passing,  every  particle  of  the  air  comes  into 
contact  with  the  water  drops;  the  almost  invisible  particles  of 
dust  adhere  to  the  water  and  are  carried  away  leaving  the  air 
washed  clean.  In  addition  to  freeing  the  air  from  dust,  the 
intimate  mixture  of  the  air  permits  of  a  ready  absorption  of  the 
water,  which  is  taken  up  to  any  per  cent,  of  saturation.  After 
leaving  the  spray  chamber,  the  moisture-laden  air  passes  through 
an  eliminator  in  which  any  unabsorbed  moisture  is  extracted. 
It  is  possible  for  air  to  become  not  only  completely  saturated 
with  water  under  the  conditions  encountered  in  a  humidifying 
plant,  but  in  addition,  the  movement  of  the  air  may  carry  along 
unabsorbed  particles  that  are  precipitated  directly  after  leaving 
the  spray  chamber.  For  this  reason  the  air  is  passed  through  an 
eliminator. 

The  eliminator  is  composed  of  a  series  of  irregular  sheet-met  a 
surfaces  so  arranged  that  the  air  is  required  to  abruptly  change 
its  direction  several  times  in  its  passage  of  a  short  distance.  The 
impact  of  the  air  against  the  surfaces  and  the  centrifugal  force 
exerted  by  the  sudden  changes  of  direction  throw  out  the  excess 
moisture  and  any  remaining  suspended  matter  the  air  may  contain. 

The  saturated  air  from  the  eliminator  passes  through  a  heater 
where  the  temperature  is  raised  to  that  of  the  rooms.  In  the 
rise  of  temperature  the  air  which  is  saturated  is  rendered  capable 
of  absorbing  more  moisture,  and  hence  has  been  dehumidified. 
The  rise  of  temperature  and  the  corresponding  decrease  in  relative 
humidity  is  intended  to  be  such  as  to  leave  in  the  finished  air 
the  desired  percentage  of  moisture. 


244  MECHANICS  OF  THE  HOUSEHOLD 

Air-cooling  Plants. — The  use  of  air-washing  and  humidifying 
plants  so  far  mentioned  has  been  confined  to  elimination  of 
dust  and  the  addition  of  moisture  to  air,  under  winter  conditions. 
The  same  type  of  apparatus,  used  in  summer,  becomes  a  cooling 
plant,  and  by  observance  of  the  necessary  requirements  may  be 
used  to  produce  agreeable  atmospheric  conditions  during  hot 
weather. 

When  used  for  such  purpose  the  air  is  washed,  by  passing  it 
through  falling  water  which  frees  it  from  dust  and  reduces  its 
temperature.  It  is  then  further  cooled  by  passing  over  cold 
surfaces  that  take  the  place  of  the  heaters  used  in  cold  weather. 
The  cooling  surfaces  are  pipe  coils  kept  cold  by  the  contained 
water  which  comes  from  the  water  supply  or  from  a  refrigerating 
plant.  The  temperature  and  humidity  are  thus  changed  to  suit 
the  requirements  of  the  conditioned  air. 

During  the  hot  weather  of  summer  the  most  disagreeable 
atmospheric  condition  is  that  caused  by  humidity  near  saturation, 
at  a  time  of  relatively  high  temperature.  Under  such  conditions 
the  cooling  plant  not  only  cools  the  air,  but  causes  a  precipitation 
of  the  moisture  on  the  cold  surfaces  which  are  kept  below  the 
dew-point.  The  air  is  cooled  and  dehumidified  to  a  point  such 
that  the  conditioned  air  produces  an  agreeable  atmosphere. 
The  regulation  of  the  degree  to  which  the  air  is  cooled  is  accom- 
plished by  the  same  general  methods  as  are  used  in  heating. 

Humidity  Control. — The  method  of  regulating  atmospheric 
humidity  in  a  humidifying  plant  will  be  determined  by  the  con- 
ditions under  which  it  is  intended  to  work.  There  are  a  variety 
of  means  employed  that  may  be  used  to  bring  about  the  same 
effects,  each  of  which  is  particularly  suited  to  certain  require- 
ments. 'The  present  object  is  to  describe  the  essential  features  of 
airconditioning  plants,  by  use  of  illustrations  representing  each 
of  the  three  methods  mentioned  above.  That  of  the  ventilation 
of  a  school  building  under  winter  conditions  will  be  taken  as 
an  example. 

In  Fig.  174  is  shown  a  heating  and  ventilating  system  in  which 
the  air  conditioning  is  accomplished  by  automatic  regulators 
for  both  temperature  and  humidity.  The  plant  occupies  a  room 
in  the  basement,  and  a  room  directly  above  illustrates  the  condi- 
tions that  prevail  in  all  of  the  other  rooms  of  the  building.  The 


VENTILATION 


245 


principal  features  of  the  plant  are  the  fan  G,  which  supplies  the 
air;  the  hot-air  furnace  H,  which  furnishes  the  heat;  and  the 
water  spray  S,  which  provides  the  moisture  with  which  the  air 
is  humidified. 

The  air  is  drawn  in  at  A  to  a  room  in  which  a  motor-driven 
fan  G  forces  the  supply  through  the  heating  apparatus  into  the 
building.  The  air  after  leaving  the  fan  passes  through  a  cold- 
air  duct  C  to  the  heating  surfaces  H  to  be  warmed.  The  air 
in  passing  over  the  heating  surfaces  is  raised  to  a  degree  consider- 
ably above  the  temperature  of  the  rooms.  The  hot  air  leaving 
the  heater  H  enters  the  tempered  air  chamber  T  through  the  pas- 
sage K.  A  damper  M  provides  means  for  also  admitting  cold 


FIG.   174. — Furnace  blast  system  of  heating,  with  temperature  regulation  and 

humidity  control. 

air  to  the  chamber  T  directly  from  the  fan.  The  thermostat, 
located  at  0,  is  connected  with  a  pneumatic  motor  V  (similar  to 
Fig.  170)  which  regulates  the  supply  of  cold  and  hot  air  from  K 
and  M  to  suit  the  desired  temperature  of  the  air  supply  for  the 
rooms  above.  The  arm  of  the  motor  V  is  so  arranged  that  an 
upward  movement  opens  the  cold-air  and  closes  the  hot-air 
passages;  the  downward  movement  produces  the  opposite  effect. 
The  motor  V  thus  controls  the  temperature  of  the  air. 

In  this  system  the  air  is  humidified  by  a  direct  water  spray 


246 


MECHANICS  OF  THE  HOUSEHOLD 


marked  S  in  the  drawing.  A  part  of  the  hot  air  from  the  heater 
H  may  escape  through  the  damper  W  and  absorb  water  on  its 
way  to  the  duct  Z),  which  takes  the  air  to  the  room  above,  where 
it  enters  through  the  register  E.  This  air  as  it  comes  from  the 
heater,  being  hot,  will  absorb  a  larger  amount  of  water  than  the 
air  could  hold  when  cooled  to  room  temperature;  for  this  reason 
only  a  part  of  the  air  supply  is  humidified.  The  supply  of  the 
hot  humid  air  is  admitted  to  the  duct  D  in  such  quantity  as  will 
produce  the  desired  degree  of  humidity  in  the  rooms. 

The  degree  of  room  temperature  is  governed  by  the  thermo- 
stat, in  the  room,  which,  by  means  of  the  motor  N,  controls  the 


FIG.  175. — Direct  steam  heating  system  with  mechanical  fan- blast  v*entilation, 
temperature  regulation  and  humidity  control. 

damper  F.  This  damper  admits  hot  humid  air  and  the  tempered 
air  from  the  chamber  T  in  proper  proportion.  At  any  time  the 
humidity  of  the  air  in  the  room  reaches  the  maximum  amount  for 
which  it  is  set,  the  humidostat,  through  its  motor,  closes  the  valve 
R,  which  controls  the  water  supply  to  the  spray  nozzle,  and  the 
moisture  in  the  air  is  reduced  until  a  further  amount  is  demanded. 
With  apparatus  of  this  kind  the  temperature  and  humidity  may 
be  kept  practically  constant. 

Fig.  175  shows  another  arrangement  of  a  similarly  controlled 
plant  in  which  steam  is  used  for  humidifying  the  air.     The  air  is 


VENTILATION  247 

admitted  at  A,  from  whence  it  passes  through  a  steam-heating 
coil  S,  which  raises  it  to  a  predetermined  temperature.  The 
steam  jets  are  arranged  at  H,  for  providing  the  necessary  mois- 
ture. The  humidostat  through  a  motor  valve  V  governs  the 
amount  of  steam  that  is  permitted  to  enter  the  humidifying 
chamber.  A  thermostat  located  in  the  air  duct  at  B  controls  the 
temperature  of  the  air  sent  to  the  rooms  by  regulating  the  amount 
of  heat  given  out  by  the  steam  coils  S.  This  control  is  made 
still  more  sensitive  by  use  of  a  cold-air  bypass.  The  damper  D 
is  opened  by  a  motor  valve  to  admit  cold  air  at  the  same  time 
the  steam  is  shut  off  from  the  heater  coils. 

In  this  plant  the  ventilating  air  is  not  intended  to  supply  all 
of  the  heat  to  the  rooms.  A  thermostat  on  the  wall  controls  the 
room  temperature  by  regulating  the  amount  of  steam  admitted 
to  the  radiators.  In  the  ventilating  plant  previously  described, 
all  of  the  heat  for  the  building  is  supplied  through  the  ventilating 
system;  in  the  plant  shown  in  Fig.  175,  the  heating  apparatus 
which  warms  the  building  is  entirely  separate  and  may  be  used 
when  the  ventilating  system  is  inoperative. 

The  humidity  is  controlled  by  admitting  saturated  air  to  the 
warmer  air  of  the  rooms  in  such  quantity  as  will  produce  the 
desired  mixture.  The  humidostat,  on  the  left-hand  wall,  regu- 
lates the  quantity  of  moisture  by  opening  or  closing  the  steam 
valve  V  as  occasion  requires. 

Another  example  of  air-conditioning  plant  similar  in  principle 
to  that  just  described  is  often  called  the  dew-point  system.  It 
depends  for  its  action  on  a  definite  dew-point  temperature  at 
which  the  air  is  saturated  with  moisture,  before  being  heated  to 
room  temperature.  The  air  to  be  conditioned  is  first  warmed,  by 
passing  through  a  set  of  tempering  coils,  to  a  degree  at  which  it 
will  contain  the  necessary  moisture  when  saturated.  After 
saturation  the  temperature  is  raised  by  a  second  set  of  heating 
coils  to  the  room  temperature,  the  moisture  contained  being  right 
to  give  the  desired  humidity. 

To  illustrate,  suppose  that  it  is  desired  to  maintain  a  constant 
humidity  of  50  per  cent,  saturation  at  70°F.  in  the  building.  The 
temperature  at  which  the  air  must  be  saturated,  to  contain  4 
grains  of  moisture  per  cubic  foot,  is  found  in  the  table  on  page  199 
to  be  48°F. 


248 


MECHANICS  OF  THE  HOUSEHOLD 


The  entering  air  must  first  be  raised  to  that  temperature  by 
the  tempering  coils.  The  air  then  enters  the  spray  chamber 
where  it  absorbs  moisture  to  saturation,  by  contact  with  a 
multitude  of  water  particles.  This  saturated  air  now  passes 
through  a  second  set  of  heated  coils  and  takes  up  heat  sufficient 
to  raise  it  to  the  finished  temperature. 

The  dew-point  temperature  at  which  the  air  enters  the  spray 
chamber  and  the  final  temperature  are  kept  constant  by  motor- 
operated  valves  which  supply  the  heating  coils  with  the  necessary 
heat  in  the  form  of  steam.  The  motors  are  controlled  by 
thermostats,  placed  to  measure  the  temperature  of  the  air  as  it 


FIG.   176. — School  building  section  showing  a  complete   air-conditioning   plant. 

enters  the  saturator  and  the  finished  air  as  it  enters  the  rooms. 
If  these  conditions  are  now  kept  constant,  the  finished  air  will 
be  constantly  50  per  cent,  saturated. 

A  plant  of  this  character  is  illustrated  in  Fig.  176.  The  figure 
shows  the  exterior  of  the  casings  which  enclose  the  tempering 
coils  and  saturator  at  A,  the  eliminator  at  B,  and  the  heating 
coils  at  C.  This  is  another  draw-through  type  of  plant  where  a 
fan,  enclosed  in  D,  draws  the  air  through  the  conditioning 
apparatus  and  forces  it  through  the  sheet-iron  ducts  E.  The 
passages  in  the  walls — as  indicated  by  the  arrows — conduct 
the  air  through  the  register  R,  into  the  room.  The  register  S 


VENTILATION  249 

represents  the  discharge  duct  through  which  the  vitiated  air 
is  forced  from  the  room. 

In  this  system  of  air  conditioning,  all  of  the  ventilating  air  is 
to  be  saturated  with  moisture  at  a  temperature  such  that  when 
raised  to  room  temperature  will  contain  the  desired  percentage 
of  humidity.  The  saturator  occupies  the  space  between  A  and  B. 
A  number  of  spray  jets  are  arranged  to  fill  the  entire  space  with 
water  drops  that  are  moving  in  every  direction.  The  air,  as  it 
passes,  must  come  into  contact  with  the  drops  again  and  again, 
until  by  repeated  impact  each  particle  is  completely  saturated 
and  at  the  same  time  washed  free  from  dust.  It  has  already  been 
explained  that  the  movement  of  the  saturated  air  through  a  mass 
of  spray  will  carry  with  it  a  considerable  amount  of  unabsorbed 
water  that  must  be  taken  out  by  an  eliminator.  A  section  of  the 
casing  is  broken  out  at  B,  showing  the  eliminator  plates.  The 
irregular  surfaces  of  these  plates  repeatedly  change  the  direction 
of  the  passing  air,  and  the  suspended  water  or  remaining  solid 
matter -is  thrown  against  the  surfaces  where  they  adhere.  The 
moisture  accumulates  in  drops  of  water  that  run  down  the  plates 
to  the  bottom  of  the  enclosure  and  finally  into  the  sewer. 

From  the  eliminator  the  air  passes  through  the  heating  coils 
enclosed  in  C,  where  it  is  heated  to  the  necessary  temperature  for 
admission  to  the  rooms. 

The  regulation  of  the  temperature  of  the  tempering  coils  and 
heating  coils  is  accomplished  as  in  the  other  plants  described. 
The  thermostats  with  their  motors  operate  the  valves  of  the 
heaters  to  admit  steam  sufficient  to  keep  constant  temperatures 
at  the  different  parts.  The  humidity  is  maintained  at  a  con- 
stant amount  by  saturating  the  air  at  a  constant  temperature  and 
therefore  no  humidostat  is  required. 


I 

V 

CHAPTER  XII 

GASEOUS  AND  LIQUID  FUELS 

Gaseous  and  Liquid  Fuels. — Gaseous  and  liquid  fuels  used  for 
domestic  illumination  and  heating  may  be  divided  into  three 
general  classes— coal  gas,  including  carburetted  water  gas  and 
producer  gas  and  their  various  mixtures;  oil  gas,  acetylene  and 
gasoline  gas.  Of  these  the  first  is  the  most  important  as  an 
illuminating  gas,  while  for  industrial  and  domestic  purposes 
producer  gas  is  of  no  importance  as  a  fuel  gas.  Gasoline,  acety- 
lene and  oil  gases  are  generated  and  used  to  a  remarkable  extent 
in  isolated  dwellings  as  fuel  and  for  illumination. 

The  value  of  any  gas  for  domestic  purposes  will  depend  on  the 
amount  of  heat  that  is  produced  when  it  is  burned.  In  the  earlier 
days  of  its  use  coal  gas  was  employed  entirely  as  an  illuminant 
and  its  value  was  expressed  in  illuminating  power;  at  the  present 
time  the  standard  often  prescribed  by  regulation  is  that  of  its 
illuminating  capability  and  is  stated  in  candlepower.  There 
is,  however,  a  tendency  to  establish  the  more  consistent  standard 
of  expressing  the  value  of  gas  by  its  heat  value.  The  reasons  for 
this  is  the  general  use  of  mantle  gas  burners  which  depend  on  the 
heating  value  alone  for  their  efficiency  and  the  fact  that  coal  gas  is 
very  extensively  used  for  domestic  fuel. 

Coal  Gas. — Coal  gas  is  derived  from  the  solid  hydrocarbons  of 
coal  transformed  into  the  more  convenient,  gaseous  form  of  fuel 
by  means  of  distillation.  Coal  gas  was  first  made  by  distilling 
coal  from  an  iron  pot  over  a  fire  and  to  some  extent  this  is  still 
the  principle  of  the  present  practice.  The  gas  as  it  comes 
from  the  retort  is  subjected  to  a  refining  process  of  washing  and 
scrubbing  to  remove  the  undesirable  properties  when  it  is  stored 
in  a  large  gasometer  for  distribution  through  pipes  to  its  places 
of  use.  Coal  gas  is  now  used  largely  for  fuel  as  well  as  for  light- 
ing. Unless  the  heating  value  of  gas  is  regulated  by  law  in  any 
community  and  determinations  of  its  quality  are  made  regularly 

250 


GASEOUS  AND  LIQUID  FUELS  251 

by  some  competent  official,  the  amount  of  heat  contained  in  coal 
gas  is  entirely  at  the  option  of  the  manufacturer  and  manager's 
conscience.  The  value  as  given  in  the  table  on  page  252  is  the 
number  of  B.t.u.  coal  gas  should  contain.  The  heating  value  of 
any  gas  is  determined  by  burning  the  gas  in  a  calorimeter  made 
expressly  for  the  measurement  of  the  heat  of  combustion  for 
each  foot  of  the  gas  consumed. 

All-oil  Water  Gas. — In  places  where  an  abundant  supply  of 
cheap  oil  is  available,  all-oil  water  gas  has  met  with  a  great  deal 
of  favor.  It  is  made  by  atomizing  crude  oil  by  a  blast  of  steam 
in  a  heated  chamber  where  a  combination  of  the  vaporized  oil 
and  steam  form  a  gas.  In  general  the  gas  resembles  coal  gas 
and  as  given  in  the  table  on  page  252  is  slightly  higher  in  heating 
value. 

Pintsch  Gas. — One  of  the  commercial  adaptations  of  oil  gas  is 
that  of  the  Pintsch  process  of  compressing  the  gas  in  tanks  for 
transportation.  In  the  Pintsch  process,  the  gas  is  subjected  to 
a  pressure  of  10  atmospheres — about  150  pounds.  This  con- 
densation permits  a  sufficiently  large  volume  of  gas  to  be  stored 
in  tanks  as  to  make  possible  the  lighting  of  railroad  trains,  etc., 
by  gaslight.  The  pressure  of  the  gas  is  reduced  by  an  automatic 
regulating  valve  to  that  required  by  the  burner.  The  flame  is 
very  much  the  same  as  that  produced  by  coal  gas. 

Blau  Gas. — Another  commercial  adaptation  of  oil  gas  is  that 
known  as  Blau  gas.  In  this  process  of  storage  the  gas  is  sub- 
jected to  100  atmospheres  of  pressure — about  1500  pounds.  This 
pressure  is  sufficient  to  liquefy  the  gas  and  as  a  result  a  large 
amount  can  be  transported  in  a  relatively  small  space.  Accord- 
ing to  Fulweiler  1  gallon  of  the  liquefied  gas  will  yield  about  28 
cubic  feet  of  the  expanded  gas  and  there  will  remain  a  residue 
that  may  run  up  to  9  per  cent. 

Water  Gas. — When  the  vapor  of  water  is  brought  into  con- 
tact with  incandescent  carbon,  the  water  is  decomposed  and 
sufficient  carbon  is  absorbed  to  produce  a  fuel  gas.  Its  manu- 
facture depends  on  the  decomposition  that  takes  place  when 
steam  is  blown  into  a  bed  of  incandescent  coal.  The  gas  made 
by  this  reaction  is  a  water  gas,  but  due  to  the  fact  that  when 
burned  it  gives  a  blue  flame,  it  is  known  as  "blue  gas."  It  has 
a  heating  value  of  about  300  B.t.u.  per  cubic  foot,  and  as  com- 


252 


MECHANICS  OF  THE  HOUSEHOLD 


pared  with  coal  gas  which  gives  622  B.t.u.  per  cubic  foot,  would  be 
reckoned  at  about  one-half  its  value  as  a  heating  agent.  Blue 
gas  may  be  rendered  luminous  by  the  addition  of  some  hydro- 
carbon that  will  liberate  free  carbon  in  the  flame  when  burned. 
This  is  accomplished  in  the  process  of  manufacture  by  the  addi- 
tion of  vaporized  oil. 

The  following  table  as  stated  by  Fulweiler  gives  the  heating 
values  of  the  gases  commonly  used  for  domestic  purposes  in 
British  thermal  units  per  cubic  foot. 

Coal  gas 622  B.t.u. 

Carburetted  water  gas 643  B.t.u. 

Pintsch  gas 1,276  B.t.u. 

Blau  gas 1,704  B.t.u. 

All-oil  water  gas 


680  B.t.u. 

Acetylene  gas 1,350  B.t.u. 


Gasoline  gas... 

Oil  gas , 

Blue  water  gas 


514  B.t.u. 

1,320  B.t.u. 

300  B.t.u. 


The  cost  and  calorific  values  as  computed  by  Dr.  Willard  of 
the  State  Agricultural  College  of  Kansas,  given  below,  shows  the 
relative  values  of  various  kinds  of  domestic  fuels. 


Wood,  20  per  cent.  H.O. 
Bitu.  coal 
Ant.  coal 
Gasoline,  sp.  gr.  68 


Cost  per 
pound 
cents 

$  5. 00  per  cord 0.167 

$4.25  per  ton 0.213 

$12. 50  per  ton 0.625 

$  0. 14  per  gallon,  5^ 

pounds...  2.470 


Kerosene,  sp.  gr.  80         $  0.11  per  gallon  6% 

pounds 1.650 

Coal  gas,  1.50  per  1000  cubic  feet 3 . 100 

Alcohol,  90  per  cent.,  50  per  gallon,  7  pounds. .     7.140 
Electricity,  0.15  per  kilowatt-hour 


Cal.  per 
Gram 


2.3 

7.5 
6.0 

10.0 


10.0 

20.0 

6.4 


Cal.  for 
1  cent 


7,620 

16,009 

4,354 

1,846 


2,753 

2,927 

404 

57.4 


The  relatively  high  heat  value  of  Blau  gas  (1704  B.t.u.)  and  the 
fact  that  it  may  be  reduced  to  a  liquid  form  for  transportation 
has  resulted  in  the  manufacture  of  small  lighting  plants  that  may 
be  used  in  pla'ces  where  other  forms  of  liquid  or  gaseous  fuel  are 
not  desirable. 

For  transportation  the  gas  is  compressed  in  seamless,  steel 
bottles  that  contain  about  20  pounds  of  liquid.  The  charged 


GASEOUS  AND  LIQUID  FUELS  253 

bottles  are  shipped  to  the  consumer  and  when  empty  are  returned 
to  the  manufacturers  to  be  refilled. 

The  entire  plant — ready  to  be  attached  to  the  distributing 
pipes  in  the  house — is  contained  in  a  steel  cabinet.  The  charged 
tanks  are  attached  to  a  larger  tank  into  which  the  liquid  gas  is 
first  expanded.  This  expansion  is  accomplished  by  an  automatic 
valve  that  maintains  a  constant  pressure  in  the  large  tank. 
With  this  plant  the  lamps  and  burners  of  the  stoves  are  operated 
as  with  city  gas — no  generating  or  preliminary  preparation 
being  necessary.  As  soon  as  the  bottles  are  exhausted  they  are 
replaced  by  others  and  the  empty  bottles  are  shipped  to  the  fac- 
tory to  be  refilled. 

Measurement  of  Gas. — When  gas  of  any  kind  is  purchased 
from  a  manufacturing  company,  the  amount  used  is  measured  by 
a  gas  meter,  located  at  the  point  where  the  gas  main  enters  the 
building.  The  readings  of  the  meter  are  taken  by  the  company 
at  stated  intervals  and  the  amount  registered  is  charged  to  the 
account  of  the  consumer.  Gas  is  sold  in  cubic  feet  and  is  so 
registered  by  the  meter.  The  price  is  quoted  by  the  manufac- 
turers at  a  definite  rate  per  thousand  cubic  feet.  The  difference 
between  the  last  two  readings  of  the  meter  furnishes  the  amount 
from  which  the  gas  bill  is  reckoned. 

The  occupants  of  a  building  are  responsible  for  all  gas  registered 
by  the  meter  and,  therefore,  should  be  acquainted  with  the 
conditions  under  which  the  gas  is  sold.  Gas  bills  are  often  the 
subject  of  dispute  because  of  failure  to  understand  the  period  of 
time  covered  by  the  amount  claimed;  again,  the  varying  length 
of  days  due  to  the  season  of  the  year  has  a  pronounced  effect 
on  the  amount  of  gas  consumed.  Lack  of  care  in  the  economical 
use  of  gas  is  probably  the  most  prolific  cause  of  disputed  bills. 

The  amount  due  for  gas  may  at  any  time  be  checked  by  the 
consumer  who  keeps  a  record  of  the  meter  readings.  At  any 
time  the  correctness  of  a  meter  is  doubted,  arrangement  may  be 
made  with  the  gas  company  to  have  it  tested  for  accuracy. 
This  is  done  in  the  office  of  the  company,  by  attaching  the  meter 
to  a  measuring  device — called  a  meter  prover — in  which  a  definite 
measured  amount  of  gas  is  passed  through  the  meter  and  com- 
parison made  with  meter  registration.  If  it  is  found  that  the 
meter  does  not  register  correctly,  the  gas  company  is  in  duty  bound 


254 


MECHANICS  OF  THE  HOUSEHOLD 


to  make  good  the  difference.  If,  however,  the  meter  is  found  to  be 
correct,  it  is  customary  to  charge  for  the  services  of  proving  the 
meter. 

Gas  Meters. — The  gas  meter  as  ordinarily  used  is  shown  in 
Fig.  177.  In  Fig.  178  the  same  meter  is  shown  with  the  top  and 
front  exposed. 

The  meter  is  operated  by  the  pressure  of  the  gas  which  enters 
at  the  inlet  pipe  on  the  left-hand  side  of  the  meter  as  you  face 
the  index.  The  gas  from  this  pipe  comes  into  the  valve  chamber 
and  passes  alternately  into  the  diaphragms  and  their  chambers, 
as  the  valve  ports  V  are  opened  and  closed  by  the  action  of  the 


FIG.  177.— Gas  meter. 


FIG.  178. — Gas  meter  show- 
ing internal  mechanism. 


meter.  The  movement  of  the  valve  in  opening  the  port  which 
admits  gas  to  the  diaphragm  closes  the  port  to  the  chamber 
which  has  filled.  The  gas  entering  the  diaphragm  expands  it 
like  a  bellows  and  forces  the  gas  out  of  the  chamber,  through 
the  middle  part  of  the  valve  into  the  outlet  pipe  F.  While  this 
action  is  going  on,  the  gas  is  entering  the  case  compartment  on 
the  opposite  side  of  the  meter  and  also  forcing  the  gas  from  its 
diaphragm  through  the  opening  F. 

While  the  meter  is  in  operation,  one  of  the  diaphragms  and 
one  of  the  case  compartments  are  filling  while  the  others  are 
emptying.  The  movement  of  the  diaphragm  discs  is  transformed 
to  the  recording  dial  by  the  connecting  levers  shown  at  the  top 


GASEOUS  AND  LIQUID  FUELS  255 

of  the  figure.  The  movement  of  these  levers  is  such  as  to  pro- 
duce a  rotary  motion  to  a  tangent  which  is  attached  to  a  shaft 
that  operates  the  recording  dial.  The  tangent  is  carried  around 
in  a  circle  by  the  action  of  the  arms  and  its  movement  is  regis- 
tered on  the  index  of  each  cycle  of  the  diaphragms. 

The  measurement  is  accomplished  by  the  displacement  of  a 
definite  amount  of  gas  with  each  movement  of  the  discs;  first, 
from  the  chamber  and  then  from  the  diaphragms. 

HOW  TO  READ  THE  INDEX 

The  index  of  a  gas  meter  looks  quite  complicated,  but  it  is 
really  a  very  simple  contrivance.  The  small  circle  on  the  top 
in  Fig.  177  is  for  testing  purposes  only  and  need  not  be  considered. 
The  dial  of  Fig.  177  is  shown  in  Fig.  177 A.  The  first  circle, 
marked  1  thousand,  registers  100  feet  for  each  figure,  1000  feet 
for  the  entire  circle.  If  the  pointer  stood  on  9  it  would  mean 
900  cubic  feet.  The  second  circle  registers  1000  for  each  figure, 
or  10,000  for  the  entire  circle.  When  the  pointer  of  the  first 
circle  has  been  around  once,  it  reaches  0  on  that  circle,  but 
the  hand  on  the  second  has  moved  to  figure  1,  showing  1000 
feet  used.  The  process  goes  on  until  the  pointer  of  the  second 
circle  has  traveled  around  and  stands  at  zero.  The  pointer  on 
the  third  circle,  however,  has  moved  to  1,  indicating  10,000. 
This  explanation  shows  the  general  plan  of  the  index.  A  few 
minutes  study  of  it  will  render  the  index  as  easy  to  read  as  the 
face  of  a  clock.  Of  course,  the  pointers  do  not  always  stand 
exactly  on  the  figures  as  they  move  from  figure  to  figure  as  the 
gas  is  used. 

Suppose  your  index  stood  like  this: 


FIG.  177^1.  —  Gas-meter  dial.     It  reads  38600  cubic  feet. 


Take  the  figure  3  on  the  100  thousand  circle,  the  figure  8  on 
the  10  thousand,  and  the  figure  6  on  the  1  thousand,  and  you  have 


256 


MECHANICS.  OF  THE  HOUSEHOLD 


30,000,  8000,  and  600,  or  38,600  feet.  To  ascertain  the  quantity 
of  gas  used  in  the  time  elapsing  between  the  readings  of  the  meter, 
subtract  the  quantity  registered  at  the  previous  reading.  Thus, 
if  the  previous  reading  was  38,600  feet,  and  the  next  reading 
40,100  feet,  the  pointers  standing  thus: 


FIG.  1775. — Gas-meter  dial.     It  reads  40100  cubic  feet. 

You  have 40,100 

Subtract  your  last  reading 38,600  and  you  find 


that  your  bill  should  be  for 1,500  feet 

When  100,000  feet  have  been  passed,  the  index  is  at  zero;  that 
is,  all  the  pointers  stand  at  0,  and  the  registration  begins  all  over 
again. 

Prepayment  Meters. — In  many  places  it  is  desirable  to  sell 
gas  in  small  quantities  and  to  prepay  the  amount  for  a  given 
supply  of  gas.  This  is  accomplished  by 
a  meter  such  as  that  of  Fig.  179.  The 
meter  is  constructed  much  the  same  as  the 
former  but  provided  with  a  mechanism 
such  that  when  a  coin — usually  25  cents — 
is  deposited,  according  to  the  printed 
directions  in  the  instrument,  an  amount 
of  gas  representing  the  proportional  cur- 
rent rate  is  allowed  to  pass  the  meter. 
The  supply  is  cut  off  as  soon  as  the 
amount  paid  for  is  used;  when  in  order 
to  receive  more  gas,  another  coin  must  be 
deposited  as  before. 
Gas-service  Rules. — The  rules  for  the  regulation  of  gas  serv- 
ice are  in  many  States  under  the  control  of  a  board  or  commis- 
sion whose  duty  it  is  to  form  codes  prescribing  the  measurement 
and  sale  of  all  public  utilities.  The  following  form,  General 
Order  No.  20,  State  Public  Utilities  Commission  of  Illinois, 


FIG.  179.— The  prepay- 
ment gas  meter. 


GASEOUS  AND  LIQUID  FUELS  257 

gives  an  idea  of  the  requirements  in  that  State  for  the  sale  of 
coal  gas. 

RULE  3.  REQUEST  TESTS. — Each  utility  furnishing  metered  service  shall 
make  a  test  of  the  accuracy  of  any  meter,  upon  written  request  by  a  con- 
sumer: Provided,  first,  that  the  meter  in  question  has  not  been  tested  by  the 
utility  or  by  the  commission  within  6  months  previous  to  such  request; 
and  second,  that  the  consumer  will  agree  to  accept  the  result  of  the  test 
made  by  the  utility  as  determining  the  basis  for  settling  the  difference 
claimed.  No  charge  shall  be  made  to  the  consumer  for  any  such  test.  A 
report,  giving  the  result  of  every  such  test,  shall  be  made  to  the  consumer. 

RULE  4.  ADJUSTMENT  OF  BILLS  FOR  METER  ERROR. — If  on  any  test  of 
a  service  meter,  either  by  the  utility  or  by  the  commission,  such  meter  shall 
be  found  to  have  a  percentage  of  error  greater  than  that  allowed  in  Rule  1 1 
(see  below)  for  gas  meters,  the  following  provisions  for  the  adjustment  of 
bills  shall  be  observed. 

(a)  Fast  Meters. — If  the  meter  is  faster  than  allowable,  the  utility  shall 
refund  to  the  consumer  a  percentage  of  the  amount  of  his  bills  for  the  6 
months  previous  to  the  test  or  for  the  time  the  meter  was  installed,  not  ex- 
ceeding 6  months,  corresponding  to  the  percentage  of  error  of  the  meter. 
No  part  of  a  minimum,  service  or  demand  charge  need  be  refunded. 

(6)  Slow  Meters. — If  the  meter  is  found  not  to  register  or  to  run  slow,  the 
utility  may  render  a  bill  to  the  consumer  for  the  estimated  consumption 
during  the  preceding  6  months,  not  covered  by  bills  previously  rendered,  but 
such  action  shall  be  taken  only  in  cases  of  substantial  importance  where  the 
utility  is  not  at  fault  for  allowing  the  incorrect  meter  to  be  in  service. 

RULE  11.  GAS-METER  ACCURACY. — (a)  Method  of  Testing. — All  tests  to 
determine  the  accuracy  of  registration  of  a  gas  service  meter  shall  be  made 
with  a  suitable  meter  prover.  At  least  two  test  runs  shall  be  made  on  each 
meter,  the  results  of  which  shall  agree  with  each  other  within  one-half 
per  cent.  (H%)- 

(c)  Allowable  Error. — Whenever  a  meter  is  tested  to  determine  the  ac- 
curacy with  which  it  has  been  registering  in  service,  it  may  be  considered  as 
correct  if  found  not  more  than  two  per  cent.  (2%)  in  error,  and  no  adjust- 
ment of  charges  shall  be  entailed  unless  the  error  is  greater  than  this  amount. 

RULE  15.  HEATING  VALUE. — Each  utility  furnishing  manufactured  gas 
shall  supply  gas  which  at  any  point  at  least  1  mile  from  the  plant,  and  tested 
in  the  place  where  it  is  consumed,  shall  have  a  monthly  average  total  heating 
value  of  not  less  than  565  B.t.u.  per  cubic  foot,  and  at  no  time  shall  the  total 
heating  value  of  the  gas  at  such  point  be  less  than  530  B.t.u.  per  cubic  foot. 

To  arrive  at  the  monthly  average  total  heating  value,  the  results  of  all 
tests  made  on  any  one  day  shall  be  averaged  and  the  average  of  all  such  daily 
averages  shall  be  taken  as  the  monthly  average. 

RULE  8.  RAILROAD  COMMISSION  OF  WISCONSIN. — Each  utility  furnishing 

gas  service  must  supply  gas  giving  a  monthly  average  of  not  less  than  600 

B.t.u.  total  heating  value  per  cubic  foot,  as  referred  to  standard  conditions 

of  temperature  and  pressure.     The  minimum  heating  value  shall   never 

17 


258 


MECHANICS  OF  THE  HOUSEHOLD 


fall  below  550.     The  tests  to  determine  the  heating  value  of  the  gas  shall  bo 
made  anywhere  within  a  1-mile  radius  of  the  center  of  distribution. 

Gas  Ranges. — Gas  ranges  and  all  other  heaters  using  gas  as  a 
fuel  are  constructed  to  utilize  the  principle  of  the  Bunsen  burner. 

Fig.  180  illustrates  the  type  of 
burner  used  in  the  Jewel  gas 
range.  This  represents  the 
form  adapted  to  the  top  bur- 
ners for  all  direct-contact  cook- 
ing 'or  heating.  The  burners 
are  of  different  sizes  and  ar- 
ranged as  they  appear  in  Fig. 
181.  This  picture  shows  the 
top  of  the  range  as  seen  from 
above,  looking  directly  down- 
ward. The  gas  supply  pipe 
and  individual  valves  for  each 
burner  are  in  position  as  they 
appear  in  front  of  the  range. 

In  operation,  the  nozzles  of  the  gas  valves  stand  directly  in 
front  of  the  opening  G,  in  Fig.  180.     The  stream  of  gas  in  passing 


FIG. 


180. — Detroit    Jewel    one-piece, 
star-shaped  burner. 


FIG.   181. 


FIG.   182. 


FIG.   181. — Showing  top  burners  and  valve  attachment  of  a  gas  stove. 

FIG.   182. — Section  showing  arrangement  of  oven  burners  and  lighter  of  a  gas 


into  the  burner  induces  a  flow  of  air  through  the  opening  A .  The 
mixture  of  gas  and  air  is  such  as  will  burn  with  the  characteristic 
Bunsen  flame  without  smoke. 


GASEOUS  AND  LIQUID  FUELS  259 

The  oven  burners  are  different  in  form  but  the  individual 
flames  are  the  same  as  those  of  the  top  burners.  They  extend 
across  the  oven  as  shown  in  Fig.  182.  In  this  the  top  of  the 
oven  is  removed  and  burners  as  seen  are  viewed  from  above. 

The  top  burners  are  lighted  by  direct  application  of  a  burning 
match  but  the  oven  burners  must  be  lighted  by  first  igniting  a 
special  torch  or  "  pilot  lighter."  The  middle  gas  valve  of  Fig. 
182  is  turned  and  the  torch  lighted,  then  the  other  valves  are 
opened  and  the  jets  are  instantly  ignited.  As. soon  as  they  are 
burning  the  pilot  lighter  is  extinguished  by  turning  its  valve. 

The  reason  for  this  special  lighter  is  because  of  the  possibility 
of  explosion  at  the  time  of  lighting.  The  gas  from  the  jets  is 
mixed  with  air  at  the  proper  proportion  to  be  violently  explosive 
and  if  by  chance  the  gas  should  be  turned  on  a  sufficient  time 
to  fill  the  oven  with  this  explosive  mixture  and  then  lighted, 
and  explosion  would  be  certain,  with  every  possibility  of  dis- 
astrous consequences.  All  gas  ovens  should  be  lighted  in  a 
manner  similar  to  that  described. 

Lighting  and  Heating  with  Gasoline. — The  remarkable  growth 
of  modern  cities,  the  building  of  small  towns  in  the  west,  and  the 
improvement  in  suburban  and  rural  homes  has  created  a  demand 
for  efficient  means  of  illumination  in  the  form  of  small  household 
lighting  plants.  The  development  and  improvement  in  electric 
lighting  has  induced  an  equal,  if  not  greater,  improvement  in 
gas  lighting.  Up  to  the  year  1875,  the  open-flame  gas  jet 
represented  the  most  improved  form  of  city  lighting.  Then  came 
electricity,  which  for  a  time  bade  fair  to  supplant  all  other 
forms  of  illumination ;  but  the  relative  high  cost  of  electric  light- 
ing, even  with  the  advantages  it  afforded,  was  a  stimulus  to 
improvement  in  less  expensive  forms  of  illuminants. 

The  invention  of  the  incandescent-mantle  gas  burner  enor- 
mously increased  the  opportunities  for  gas  lighting  and  opened 
an  inviting  field  of  endeavor.  In  a  relatively  short  time,  three 
distinct  types  of  gasoline  lighting  plants  for  household  illumina- 
tion came  into  common  use,  with  a  great  number  of  different 
systems  in  each  type.  As  a  means  of  economical  illumination 
the  only  rival  of  any  consequence  to  the  small  gasoline-gas  plant 
of  today  is  acetylene.  The  dangers  attending  the  use  of  these 
agents  of  illumination  have  been  rapidly  eliminated,  until  today— 


260  MECHANICS  OF  THE  HOUSEHOLD 

when  intelligently  managed — they  are  fully  as  safe  as  any  other 
means  of  artificial  lighting.  Gasoline  plants  are  now  in  common 
use  in  cities  where  competition  with  all  other  forms  of  illumina- 
tion require  excellence  in  service  to  hold  an  established  place. 

In  order  that  any  mechanical  appliance  may  be  used  with  the 
best  results,  its  principle  of  operation  and  mechanism  must  be 
thoroughly  understood.  In  the  case  of  gasoline  plants,  not  only 
familiarity  with  the  mechanism  should  be  acquired  but  an 
intimate  knowledge  of  gasoline  and  its  characteristic  properties 
should  be  gained,  that  the  peculiarities  of  the  plant  may  be  more 
fully  comprehended. 

Gasoline  is  the  first  distillate  of  crude  petroleum;  that  is,  in 
the  process  of  separation,  the  crude  petroleum  is  distilled  from 
a  retort  and  the  condensed  vapors  at  different  degrees  of  tem- 
perature form  the  various  grades  of  gasoline,  kerosene,  lubricating 
oil,  paraffin,  etc.  The  crude  oil  is  placed  in  the  still  and  heated; 
the  distillate  that  first  comes  from  the  condenser,  at  the  lowest 
temperature  of  the  still,  is  gasoline  of  a  light  spiritous  nature. 
As  the  process  of  distillation  continues,  this  part  of  the  petroleum 
is  entirely  driven  off  and  it  is  necessary  to  raise  the  temperature 
of  the  still  in  order  to  vaporize  an  additional  portipn  of  the  oil. 
There  is  no  distinct  line  of  separation  between  the  gasoline  that 
first  comes  from  the  condenser  and  that  which  comes  over  after 
the  temperature  is  raised,  except  that  it  is  less  of  a  spiritous 
nature  and  contains  more  oily  matter.  As  the  temperature  of  the 
retort  is  gradually  raised,  the  distillate  contains  less  and  less  of 
the  spiritous  and  constantly  more  of  the  oily  matter. 

In  order  to  grade  gasoline  for  the  market,  the  standard  adopted 
was  that  of  relative  density.  The  distillations  produced  at 
various  temperatures  are  mixed  to  produce  various  densities 
which  form  definite  grades  of  gasoline.  The  Beaume  hydrometer 
is  a  scale  of  relative  specific  gravities  in  which  the  different 
densities  are  expressed  in  degrees.  The  highest  grade  of  gasoline 
produced  by  the  first  distillation  is  90°Be. ;  that  is,  the  hydrome- 
ter will  sink  in  the  gasoline  to  90°  on  the  scale.  As  the  tem- 
perature of  the  retort  is  gradually  raised,  the  distillate  becomes 
heavier  and  the  next  commercial  grade  is  86°  gasoline.  The 
86°  gasoline  contains  a  greater  proportion  of  oily  matter  and  a 
less  amount  of  that  of  a  spiritous  nature.  The  next  commercial 


GASEOUS  AND  LIQUID  FUELS  261 

grade  that  is  produced,  as  the  temperature  is  raised,  is  76°  gaso- 
line, a  still  highly  volatile  spirit  but  containing  more  oil  than 
the  last.  This  process  is  kept  up  until  there  is  an  amount  of 
oil  in  the  distillate  that  can  no  longer  be  termed  gasoline,  when 
kerosene  is  distilled  from  the  retort. 

The  following  descriptions  of  gasoline  and  kerosene  by  B.  L. 
Smith,  State  Oil  Inspection  Chemist  of  North  Dakota,  gives  a 
definite  idea  of  their  properties  and  the  requirements  of  the  law 
in  their  regulation  and  sale. 

"  Gasoline  is  formed  by  the  condensation  of  vapor  that  passes  off  at 
comparatively  low  temperatures  during  the  distillation  of  crude  petro- 
leum. It  has  been  common  practice  among  refiners  to  collect  as  'straight' 
gasoline  all  that  distillate  having  a  specific  gravity  above  60°Be*.  At 
present,  the  name  applies  broadly  to  all  the  lighter  products  of  petroleum 
above  50°Be.  in  gravity,  including  products  obtained  from  the  'casing- 
head'  gases  of  oil  wel^s,  by  methods  of  compression  and  cooling,  and 
also  the  'cracked'  gasoline  formed  by  the  decomposition  of  heavier 
oils  when  subjected  to  high  temperature  and  pressure. 

"It  has  been  the  custom  to  grade  and  sell  gasoline  according  to 
'high'  or  'low'  gravity  test.  Recent  study  and  investigation  has 
shown  that  specific  gravity  in  itself  is  of  very  little  value  in  deter- 
mining the  quality  of  a  gasoline.  It  may  be  taken  as  an  index  of  other 
properties,  particularly  its  volatility,  if  information  as  to  its  source 
and  method  of  production  are  at  hand;  but  under  present  market 
conditions  a  specific-gravity  determination  is  entirely  inadequate. 
The  specific-gravity  test  alone  may  give  a  high  rating  to  a  poor  gasoline 
and  a  low  rating  to  a  good  one.  It  has  been  discarded  as  a  standard 
of  comparison  by  the  U.  S.  Bureau  of  Mines.  It  indicates  nothing 
definite  about  the  quality  of  a  gasoline  and  in  many  cases  it  does  not 
even  approximate  relative  values.  Volatility,  that  is,  the  ease  with 
which  it  vaporizes,  is  the  fundamental  property  that  determines  the 
grade,  quality,  and  usefulness  of  gasoline.  The  Beaume"  test,  however, 
must  remain  the  standard  for  grading  gasolene  until  a  more  definite 
measure  is  adopted. 

"The  Oil  Inspection  Law  (1917)  for  the  State  of  North  Dakota, 
states,  that :  'all  gasolines,  sold  or  offered  for  sale  in  this  State  for  house- 
hold use,  shall,  when  one  hundred  cubic  centimeters  are  subjected  to 
a  distillation  in  a  .flask — as  described  for  distilling  of  oil — show  not 
less  than  three  (3)  per  cent,  distilling  at  one  hundred  and  fifty-eight 
(158)  degrees  Fahrenheit,  and  there  shall  not  be  more  than  six  (6) 
per  cent,  residue  at  two  hundred  and  eighty-four  (284)  degrees  Fahren- 


262  MECHANICS  OF  THE  HOUSEHOLD 

heit,  which  shall  be  known  as  the  chemical  test  for  gasoline  sold  or 
offered  for  sale  in  this  State  for  domestic  purposes.' 

"  Gasoline  for  household  purposes,  as  for  use  in  cold-process  lighting 
systems  should  contain  not  more  than  a  very  slight  amount  of  constitu- 
ents that  do  not  vaporize  readily.  It  is  obvious  that  a  gasoline  for 
cleaning  or  drying  purpose  should  contain  no  oily  or  kerosene  distillate. 
On  the  other  hand,  the  gasoline  for  use  in  a  gasoline  stove  or  other 
generator,  where  heat  is  employed  in  its  vaporization,  may  contain  a 
considerable  amount  of  the  less  volatile  oils.  The  amount  of  gasoline 
sold  for  household  use  is  in  very  minor  proportion  to  the  immense 
quantity  used  for  motor  purposes. 

"No  hard  and  fast  line  differentiates  good  motor  gasoline  from 
bad.  In  fact  standards  of  quality  seem  to  be  varying  with  advances 
in  engine  design,  so  that  what  once  was  poor  gasoline  can  now  be 
successfully  used.  Improvement  in  carburetors  seem  to  be  keeping 
pace  with  the  ever  increasing  amount  of  kerosene  in  the  ordinary  motor 
gasoline. 

"  Gravity  test  cannot  be  relied  upon  as  indicating  the  kerosene 
content.  In  the  laboratories  of  the  Oil  Inspection  Department  for 
the  State  of  North  Dakota,  there  have  been  examined  two  gasolines 
of  the  same  gravity,  56.2°Be.  at  60°F.,  but  which  contains  31  per  cent, 
and  62  per  cent,  of  kerosene  respectively,  and  their  distillation  range 
is  quite  different.  On  the  other  hand,  there  are  other  gasolines  whose 
boiling  range  is  nearly  parallel  and  similar,  yet  whose  gravities  are  50.2° 
Be",  and  59.2°Be.  respectively.  Also  a  gasoline  and  a  kerosene  having 
a  difference  in  gravity  of  but  l°Be.  and  a  difference  of  nearly  100°F. 
in  the  temperature  at  which  they  begin  to  boil  and  a  difference  at  200°F. 
in  the  temperature  at  which  all  had  distilled  over.  The  so-called  'low'- 
test  gasolines  average  between  35  per  cent,  and  40  per  cent,  kerosene. 
The  chief  element  of  advantage  in  the  so-called  'high '-test  gasolines 
seems  to  be  that  they  yield  a  maximum  efficiency  over  a  larger  range  of 
engine  conditions. 

"We  have  a  sample  of  gasoline  sold  as  'high'-test  gasoline  which 
contains  29  per  cent,  of  kerosene.  Indeed  it  has  a  high  Beaume  gravity 
(63.70)  compared  to  the  average  low-gravity  gasolines  on  the  market, 
and  it  also  contains^  large  amount  (14  per  cent.)  of  very  easily  volatile 
constituents.  Such  a  product  seems  to  be  a  blend  of  very  light  'casing- 
head'  stock  with  kerosene  of  low  boiling  range  to  give  the  'high'  gravity. 

"It  is  desirable  that  a  gasoline  should  contain  a  certain  percentage 
of  very  low-boiling  constituents,  so  that  engines  may  start  more  readily, 
especially  in  unfavorable  conditions  of  weather  or  climate;  but  a  large 
proportion  would  be  undesirable  because  of  loss  through  evaporation 


GASEOUS  AND  LIQUID  FUELS  263 

and  the  liability  of  accidental  ignition  and  explosion.  A  reasonable 
amount  of  light  volatile  material  would  probably  be  about  33^  per  cent. 
Again  a  reasonably  low  percentage  of  the  very  less  volatile  constituents 
is  desirable  to  insure  complete  vaporization  at  a  not  too  high  tempera- 
ture, say  not  more  than  10  per  cent.;  but  such  a  gasoline  would  be  ex- 
pensive. The  producers  and  refiners  claim  that  the  present  immense 
demand  necessitates  the  mixture  of  low-boiling  kerosene  constituents 
with  the  true  gasoline  fraction. 

"Kerosene. — The  character  of  this  fuel  is  best  understood  by  compar- 
ing it  with  gasoline,  which  it  in  general  resembles,  except  that  it  is  much 
less  volatile.  It  is  obtained  from  crude  petroleum  at  a  temperature 
just  above  that  (300°F.)  at  which  gasoline  passes  off.  Its  chief  use  is 
as  an  illuminant  in  lamps.  It  is  also  increasingly  used  as  a  fuel  in 
cooking  stoves,  small  portable  heaters,  and  as  a  motor  fuel  for  engines 
and  tractors. 

"The  laws  of  most  States  stipulate  certain  tests  which  kerosene  must 
meet  in  order  to  be  approved  for  general  sale.  These  tests  include 
color,  flash  point,  fire  test,  sulphur  determination,  and  candlepower 
tests.  The  North  Dakota  Oil  Inspection  Law  (1917)  specifies  that 
the  color  shall  be  water-white  when  viewed  by  transmitted  light  through 
a  layer  of  oil  4  inches  deep.  It  shall  not  give  a  flash  test  below  100°F. 
and  shall  not  have  a  fire  test  below  125°F.  Such  illuminating  oils  shall 
not  contain  water  or  tar-like  matter,  nor  shall  they  contain  more 
than  a  trace  of  any  sulphur  compound.  The  photometric  test,  when 
burning  under  normal  conditions,  shall  not  show  a  fall  of  more  than 
25  per  cent,  in  candlepower  in  a  burning  test  of  not  less  than  6  hours 
nor  more  than  8  hours'  duration,  consuming  95  per  cent,  of  the  oil. 

"The  flash  point  of  an  oil  is  the  lowest  temperature  at  which  vapors 
arising  therefrom  ignite,  without  setting  fire  to  the  oil  itself,  when  a 
small  test  flame  is  quickly  approached  near  the  surface  in  a  test  cup 
and  quickly  removed. 

"The  fire  test  of  an  oil  is  the  lowest  temperature  at  which  the  oil 
itself  ignites  from  its  vapors  and  continues  to  burn  when  a  test  flame 
is  quickly  approached  near  its  surface  and  quickly  removed. 

"When  oils  containing  sulphur  are  burned,  the  sulphur  is  thrown 
off  in  the  form  of  gaseous  sulphur  compounds.  Because  of  their 
poisonous  nature  and  their  bleaching  and  disintegrating  action  on 
clothing,  hangings,  wall  coverings,  etc.,  it  is  obvious  that  to  safe- 
guard the  health  and  preserve  the  furnishings  of  the  home,  illuminating 
oils  should  contain  not  more  than  a  trace  of  sulphur  compounds,  and 
that  their  flash  and  fire  limits  should  be  high  enough  to  insure  safety 
in  ordinary  use  in  lamps  and  stoves. 


264  MECHANICS  OF  THE  HOUSEHOLD 

"The  law  further  specifies  as  to  the  boiling  limits  of  kerosene:  'It 
shall  be  the  duty  of  the  State  Oil  Inspector  ...  to  have  chemical 
tests  made  .  .  .  demonstrating  whether  or  no  such  oils  contain 
more  than  4  per  cent,  residue  after  being  distilled  at  a  temperature  of 
570°F.,  and  shall  not  contain  more  than  6  per  cent,  of  oil  distilling  at 
310°F.,  when  one  hundred  cubic  centimeters  of  the  oil  is  distilled  from 
a  side-neck  distilling  flask'  of  certain  specified  dimensions. 

"This  is  to  insure  the  kerosene  against  an  excess  of  easily  inflam- 
mable material  of  the  gasoline  range  and  thus  render  it  dangerous  to 
the  user.  In  addition  it  is  to  insure  against  an  undue  proportion  of 
heavy  constituent  of  lubricating  oil  distillate,  which  would  clog  the  wick 
and  reduce  the  efficiency,  heating  and  illuminating  value  of  the  oil." 

LIGHTING  AND  HEATING  WITH  GASOLINE 

The  extended  use  of  gasoline  as  a  lighting  and  heating  agent, 
has  brought  about  the  development  of  a  great  number  of  me- 
chanical devices  that  are  intended  to  furnish  the  house  with  an 
efficient  source  of  illumination  and  at  the  same  time  provide 
the  kitchen  with  a  convenient  and  relatively  inexpensive  fuel. 
These  machines  are  generally  simple  in  mechanical  construction 
and  so  designed  as  to  eliminate  most  of  the  dangers  involved 
in  the  use  of  gasoline.  Jn  operation,  they  require  a  minimum 
amount  of  attention  when  suited  to  the  purpose  for  which  they 
are  intended.  That  the  object  of  the  plants  is  attained  is  attested 
by  the  great  number  in  use  and  the  degree  of  satisfaction  afforded 
the  users. 

The  three  systems  of  gasoline  lighting  referred  to  above  are 
known  commercially  by  terms  which  are  characteristic  of  the 
process  involved: 

1.  The  cold-process  system,  in  which  the  gasoline  is  vaporized, 
at  the  temperature  of  an  underground  supply  tank,  and  after 
being  mixed  with  the  required  amount  of  air  is  sent  through  the 
building  in  ordinary  gas  pipes  exactly  as  in  the  case  of  city  gas. 

2.  The  hollow-wire  system,  in  which  the  gasoline  is  sent  from 
the  supply  tank  to  the  burners  in  a  liquid  form,  where  it  is  vapor- 
ized by  heat   and  the  vapor   mixed  with  the  necessary  air  to 
afford  complete  combustion. 

3.  The  central-generator  or  tube  system,  in  which  the  gasoline  is' 
sent  to  a  central  generator  from  a  supply  tank  and  there  vapor- 


GASEOUS  AND  LIQUID  FUELS  265 

ized  by  heat,  at  the  same  time  being  mixed  with  air  in  sufficient 
amounts  to  render  it  a  completely  combustible  gas  without 
further  dilution. 


THE  COLD-PROCESS  GAS  MACHINE 

The  gas  machine  of  the  cold-process  type  is  so  constructed  that 
air  is  forced  through  a  tank  or  carburetor,  containing  gasoline 
and  remains  in  its  presence  until  saturated  with  gasoline  vapor. 
This  saturated  air  is  afterward  diluted  with  additional  air,  to 
produce  a  quality  of  gas  that  contains  proportions  of  air  and  gaso- 
line vapor  which  will  produce  complete  combustion  when  burned 
with  an  open  flame. 

Combustion  is  a  rapid  chemical  change  in  which  heat  is  evolved 
due  to  the  union  of  carbon  and  oxygen.  If  the  carbon  is 
completely  oxidized,  the  combination  produces  carbon  dioxide 
(CO 2)  and  the  greatest  amount  of  heat  is  evolved. 

Gasoline  being  a  highly  volatile  liquid  will  vaporize  at  tem- 
peratures as  low  as  —  10°F.,  but  as  the  temperature  is  higher 
vaporization  will  be  more  rapid.  In  a  confined  space,  at  rela- 
tively low  temperature,  such  as  the  carburetor  of  a  gas  machine, 
the  vaporization  will  at  first  be  very  rapid;  but  after  the  more 
highly  spiritous  portion  has  been  evaporated,  a  considerable 
part,  even  of  the  lighter  grades,  will  be  vaporized  very  slowly.  In 
the  cold-process  machines,  only  the  lighter  grades  can  be  used 
with  success  and  even  then,  in  inefficient  machines,  a  portion  of 
the  lesser  volatile  gasoline  will  have  to  be  thrown  away.  For 
this  reason  and  for  others  that  will  appear  later,  it  is  advisable  to 
consider  very  closely  the  working  properties  of  the  entire  plant. 

In  order  to  obtain  gas  that  will  always  be  of  the  same  quality 
and  at  the  same  time  use  gasoline  in  an  efficient  manner,  the  gas 
machine  must  be  composed  of  three  essential  parts:  the  blower, 
the  carburetor  and  the  mixer. 

The  blower  is  that  part  of  the  machine  which  supplies  air  for 
absorbing  the  gasoline  vapor  and  maintaining  a  constant  pressure 
on  the  system.  It  is  usually  made  in  the  form  of  a  rotary  pump, 
the  motive  power  for  which  is  a  heavy  weight.  The  pump  may, 
however,  be  driven  by  water  pressure  furnished  by  city  water 
pipes  or  other  water  supply. 


266 


MECHANICS  OF  THE  HOUSEHOLD 


The  carburetor  is  a  tank  which  contains  the  supply  of  gasoline 
and  is  so  constructed  as  to  permit  the  air  from  the  blower  to 
most  readily  take  up  the  gasoline  vapor.  It  should  be  so  ar- 
ranged that  when  the  contained  gasoline  becomes  old  and  less 
volatile,  the  air  may  remain  in  its  presence  a  sufficient  time  to 
become  saturated  by  slow  absorption. 

The  mixer  is  that  part  of  the  machine  which  regulates  the 
amount  of  gasoline  vapor  contained  in  the  gas  entering  the  dis- 


1    Carburator 


2  Mixer 

3  Blower 

4  Weight 

5  Gas  Range 

6  Water  Heater 

7  Water  Tank 


FIG.   183. — Cold-process  system  of  gasoline  lighting  with  kitchen  range  and  water 

heater. 

tributing  pipes.  In  order  to  satisfactorily  perform  its  function, 
it  should  be  so  arranged  as  to  permit  a  constant  amount  of  gaso- 
line vapor  to  enter  the  mixture  which  composes  the  finished 
gas.  This  amount  should  be  such  as  to  produce  a  bright  clear 
flame  in  an  open  gas  jet.  If  the  gas  contains  too  great  an  amount 
of  gasoline  vapor,  the  flame  will  smoke.  If  too  little  gasoline 
vapor  is  present,  the  flames  will  be  pale  and  lacking  in  heat. 

In  Fig.  183,  the  entire  plant  is  shown  in  place.     It  occupies 
a  place  inside  the  building,  usually  in  the  basement.     In  the 


GASEOUS  AND  LIQUID  FUELS 


267 


figure  the  carburetor  is  marked  1 ;  the  mixer  2  stands  at  the  end 
of  the  blower,  which  is  numbered  3.  The  motive  power  of  the 
blower  is  furnished  by  a  heavy  weight,  which  is  raised  by  a 
block  and  tackle,  the  cord  of  which  is  attached  to  the  drum  and 
fastened  to  the  shaft  of  the  blower.  The  force  furnished  by 
the  weight  4  drives  the  blower  and  maintains  a  constant  pressure 
on  the  gas  in  the  system.  The  pipe  8  conducts  the  air  from  the 
blower  to  the  carburetor,  which  is  located  underground,  below 
the  frost  line  and  25  or  30  feet  away  from  the  building. 

The  carburetor  in  this  case  is  also  the  storage  tank,  as  shown 
in  detail  in  Fig.  184.  The  carburetor  is  divided  laterally  into 
two  or  more  compartments,  de- 
pending on  the  size  of  the  plant 
to  be  accommodated.  That 
shown  in  Fig.  184  contains  four 
compartments  and  is  intended 
for  a  large  plant.  The  construc- 
tion is  such  that  the  compart-  Air 
ments  are  only  partly  filled  with 
gasoline,  and  arranged  to  per- 
mit the  air  from  the  blower, 
which  enters  at  the  pipe  marked 
'air,  to  pass  through  each  com- 
partment in  succession,  begin- 
ning at  the  bottom,  in  order 
that  it  may  become  completely 
saturated  with  gasoline  vapor. 

As  an  additional  means  of  aiding  the  saturation  of  the  passing 
air,  the  compartments  in  this  carburetor  are  provided  with  spiral 
passages  through  which  the  air  must  pass,  so  that  when  it 
reaches  the  outlet  pipe,  marked  gas,  the  air  is  completely  filled 
with  gasoline  vapor. 

The  vapor-saturated  air  now  leaves  the  carburetor  by  pipe  9, 
in  Fig.  183,  and  enters  the  mixing  chamber  2,  where  it  is  mixed 
with  the  required  amount  of  atmospheric  air,  to  make  it  com- 
pletely combustible  when  burned  at  the  burner. 

The  mining  chamber  is  shown  in  detail  in  Fig.  185.  The 
mixing  is  done  automatically  and  the  quality  of  the  gas  is 


FIG.   184. — Carburetor  for  cold-proc- 
ess gasoline  lighting  plant. 


268 


MECHANICS  OF  THE  HOUSEHOLD 


Gas  Outlet 


Movable  Adjusting 
Weight 


uniform,  regardless  of  the  varying  conditions  of  the  attending 
temperature  and  the  quality  of  the  gasoline  in  the  carburetor. 

The  vitally  improtant  feature  of  any  gas  machine  is,  that  a 
constant  amount  of  gasoline  vapor  be  carried  to  the  burners.  If 
the  gas  contains  too  great  an  amount  of  gasoline  vapor,  a  smoky 
flame  will  be  the  result;  if  an  insufficient  amount  of  gasoline 
is  present,  the  flame  will  be  pale  and  give  out  little  light.  When 
freshly  charged,  the  gasoline  in  the  carburetor  will  vaporize  very 
readily,  and  a  large  amount  of  air  must  be  added  to  the  gas  to 
reduce  it  to  the  proper  consistency;  but  from  old  gasoline,  which 
has  lost  most  of  the  highly  volatile  matter,  a  smaller  proportion 

of  atmospheric  air  will  be  de- 
manded. For  this  reason,  a 
mixing  regulator  that  will 
always  deliver  gas  containing 
the  same  amount  of  gasoline 
vapor  is  necessary  to  give  satis- 
factory service.  The  mixer 
shown  in  Fig.  185  accomplishes 
this  office  by  reason  of  the 
specific  gravity  of  the  gas. 

As  the  air  in  the  carburetor 
takes    up    gasoline   vapor,   its 
specific     gravity    is    increased 
until  the  air  is  saturated;  and 
Al5'7,D/a^am,/lustrating  the  by  adding  the  amount  of  at- 

mixer  of  the  Detroit  cold-process  system 

of  gasoline  lighting.  mosphenc     air    necessary    for 

complete  combustion  the  weight 

is  reduced  to  a  definite  amount  which  will  be  constant.  The 
required  mixture  will,  therefore,  always  weigh  the  same  amount. 
The  principle  on  which  this  mixer  works  is  that  described  in 
physics  as  the  principle  of  Archimedes:  "that  a  body  immersed 
in  a  fluid  will  lose  in  weight  an  amount  equal  to  the  liquid  dis- 
placed." In  the  application  of  the  law,  the  gas  in  the  mixer  is 
the  fluid,  and  the  float — to  be  described — is  trie  displacing  body. 
The  mixer  in  Fig.  185,  is  shown  cut  across  lengthwise.  The 
outside  casing  is  indicated  by  the  heavy  black  lines.  The  gas 
which  leaves  the  opening  at  the  top — marked  gas  outlet — is  a 
mixture  of  gasoline  and  air  that  may  be  used  for  exactly  the  same 


Observation 
Port 


GASEOUS  AND  LIQUID  FUELS  269 

purpose  and  in  the  same  manner  as  coal  gas.  It  may  be  used 
in  open-flame  gas  jets  or  in  the  mantle  gas  lamps  for  lighting 
purposes  and  also  as  fuel  gas  for  domestic  heating.  The  gas  is 
distributed  through  the  building  in  ordinary  gas  pipes  which  are 
installed  as  for  any  other  kind  of  gas.  In  Fig.  183  the  dis- 
tributing pipes  are  indicated  by  the  heavy  lines. 

The  valve  in  the  air  inlet,  in  the  bottom  of  the  mixer,  controls 
the  amount  of  air  to  be  admitted.  The  entering  gas  from  the 
carburetor  being  heavier  than  the  desired  mixture,  will  raise  the 
float  and  in  so  doing  will  open  the  air  valve  and  allow  the  air 
from  the  blower  to  enter.  The  float  and  valve  are  so  adjusted 
that  the  desired  mixture  is  attained  when  the  balance  beam  is 
level.  Any  variation  in  the  mixture  will  change  its  weight  and 
the  valve  corrects  the  change  whether  it  be  too  much  or  too  little 
air. 

The  openings  at  the  bottom,  marked  gas  inlet  and  air  inlet, 
are  intended  for  the  admission  of  the  saturated  vapor  from  the 
carburetor,  and  the  atmospheric  air,  as  required.  The  float 
which  fills  the  greater  part  of  the  inner  space  is  a  light  sheet- 
metal  drum,  that  is  tightly  sealed  and  nicely  balanced  by  a 
counterweight  on  the  opposite  end  of  the  supending  bar.  The 
counterweight  is  made  adjustable  by  the  device  marked  movable 
adjusting  weight — in  the  drawing — which  permits  the  quantity  of 
entering  gas  to  be  slightly  changed  as  the  gasoline  in  the 
carburetor  grows  old. 

The  adjustment  of  the  counterweight  to  suit  the  gas  given 
off  from  old  gasoline  in  the  caburetor,  and  the  occasional  rewind- 
ing, to  elevate  the  blower  weight,  is  practically  all  the  attention 
this  plant  requires.  It  is  a  real  gas  plant  which  gives  every 
service  that  may  be  obtained  from  coal  gas. 

THE  HOLLOW-WIRE  SYSTEM  OF  GASOLINE  LIGHT- 
ING AND  HEATING 

The  hollow-wire  system  of  gasoline  lighting  possesses  the 
advantage  of  simplicity  in  construction  and  ease  of  installation 
that  makes  it  attractive,  particularly  for  use  in  small  dwellings. 
The  ease  with  which  plants  of  this  character  are  installed  in 
buildings  already  constructed  and  its  relatively  low  cost  has 


270 


MECHANICS  OF  THE  HOUSEHOLD 


made  it  a  popular  means  of  lighting.  The  same  principle  as  that 
used  in  the  hollow-wire  system  is  applied  to  portable  gasoline 
lamps  in  which  a  remarkably  convenient  and  brilliant  lamp  is 
made  to  take  the  place  of  the  customary  kerosene  lamp.  Small 
portable  gasoline  lamps  are  now  extensively  used  for  the  same 
purpose  as  ordinary  oil  lanterns.  These  lamps  are  convenient 
as  a  source  of  light,  make  a  handsome  appearance  and  are  rela- 
tively inexpensive  to  operate. 

The  hollow-wire  system  as  commonly  employed  is  illustrated 
in  Figs.   186  and   187.     In  the  gravity  type  of  the  system  as 


FIG.   186. — Hollow-wire  system  of  gasoline  lighting  with  gravity  feed. 

illustrated  in  Fig.  186,  the  supply  of  gasoline  is  stored  in  the 
upper  part  of  the  house  in  a  tank  T  and  conducted  to  the  burners 
below,  through  a  system  of  small  copper  tubes  as  indicated  by 
the  heavy  lines  in  the  drawing.  The  same  tank  is  used  to  supply 
the  gasoline  for  the  stove  S  in  the  kitchen  and  the  lamps  L  in 
the  different  apartments.  The  gasoline  supply  in  this  case,  is 
obtained  entirely  by  gravity.  This  type  of  plant  is  not  approved 
by  the  National  Board  of  Underwriters  but  its  use  is  quite 
generally  permitted.  The  storage  of  gasoline  in  this  form  should 
be  done  with  caution  as  carelessness  or  accident  might  lead  to 


GASEOUS  AND  LIQUID  FUELS 


271 


serious  results.  With  an  arrangement  of  this  kind  the  force  of 
gravity  gives  the  pressure  which  supplies  the  burners  below  but 
it  would  not  be  possible  to  use  the  lamps  on  the  same  floor 
with  the  tank. 

Where  it  is  desired  to  use  lamps  on  both  floors,  a  pressure 
tank  is  employed  for  supplying  the  gasoline  to  the  lamps,  as  indi- 
cated in  Fig.  187.  In  this  plant  the  pressure  tanks  S,  T  in  the  base- 


FIG.   187.— Hollow-wire  system  of  gasoline  lighting  with  pressure-tank  feed. 


ment,  furnish  the  pressure  which  forces  the  supply  of  gasoline 
through  the  small  tubes  to  the  lamps  L  in  the  different  rooms 
and  also  to  the  stove  R  in  the  kitchen. 

The  means  of  furnishing  the  pressure  for  supplying  the  gasoline 
to  the  burners  may  be  a  simple  tank  as  that  in  Fig.  188,  or  the 
more  elaborate  apparatus  shown  in  the  double  tank  of  Fig.  189. 
Either  style  will  give  good  results  but  the  double  tank  requires 
the  least  attention  in  operation  and  is  therefore  more  satisfactory 


in  use. 


The  tank  in  Fig.  188  is  made  of  sheet  metal  of  such  weight  as 


272 


MECHANICS  OF  THE  HOUSEHOLD 


will  safely  withstand  the  pressure  necessary  in  its  use.  It  is 
arranged  with  an  opening  E,  for  filling  with  gasoline,  a  pressure 
gage  for  indicating  the  air  pressure  to  which  the  gasoline  is 
subjected,  and  two  needle  valves;  C,  for  attaching  an  air  pump  and 
D,  to  which  the  hollow  wire  is  attached  for  distributing  the  gaso- 
line to  the  places  of  use.  The  tank  is  filled  with  gasoline  to 
about  the  line  A,  and  then  air  pressure  is  applied  with  an  ordinary 
air  pump  to  say  20  pounds  to  the  square  inch.  This  pressure 
will  be  much  more  than  will  be  necessary  to  force  the  gasoline 
through  the  tubes  but  it  is  intended  to  last  for  a  considerable 
length  of  time. 


No.2 


No.l 


FIG.   189. 


FIG.  188. 

FIG.   188. — Simple  gasoline  pressure-tank. 

FIG.  189. — Double-pressure  tank  for  constant  pressure  service  in  gasoline  light- 
ing systems. 

The  principle  of  operation  is  that  known  in  physics  as  Boyles 
law,  that  "the  temperature  being  constant,  the  pressure  of  a 
confined  gas  will  be  inversely  as  its  volume/'  That  is,  if  the 
tank  is  perfectly  tight,  the  pressure  above  the  line  A,  in  the  tank, 
will  gradually  become  less  as  the  gasoline  is  used  and  when  its 
level  is  at  the  line  B,  where  the  volume  is  twice  the  original 
amount,  the  pressure  will  be  one-half  what  it  was  originally, 
and  will  still  be  sufficient  to  force  the  gasoline  through  the  tubes 
to  the  lamps.  It  is  evident  that  once  the  tank  is  charged  and 
the  air  pressure  applied  it  will  require  no  further  attention 
until  a  considerable  part  of  the  gasoline  is  consumed.  If  at 


GASEOUS  AND  LIQUID  FUELS  273 

any  time  the  pressure  in  the  tank  becomes  too  low  to  feed  the 
lamps,  a  few  strokes  of  the  pump  will  raise  it  to  the  required 
amount. 

While  the  single  tank  does  the  required  work,  its  use  is  not 
perfect  because  the  pressure  is  constantly  varying.  If  a  lamp 
is  set  to  burn  at  a  definite  pressure,  any  decrease  in  the  gasoline 
supply  due  to  falling  pressure  will  change  the  amount  of  light 
given  by  the  lamp;  while  the  variation  in  the  pressure  of  the 
single  supply  tank  is  not  great,  a  more  perfect  effect  is  attained 
in  the  double  type  of  tank  as  that  of  Fig.  189. 

The  object  attained  in  the  use  of  two  tanks  differs  with  different 
manufacturers.  The  tank  shown  in  Fig.  183,  being  intended  to 
maintain  a  constant  pressure  on  the  gasoline,  is  quite  different 
from  those  described  in  Fig.  197  in  use  with  the  central-generator 
system  of  lighting,  to  be  described  later.  In  Fig.  189  tank 
No.  1  is  for  air  supply  alone  and  tank  No.  2  is  the  storage  tank 
for  gasoline.  Between  the  two  tanks  is  a  pressure-regulating  valve 
6-7,  which  keeps  a  constant  pressure  on  tank  No.  2  so  long  as  the 
air  pressure  of  the  tank  No.  1  is  equal  or  greater  than  the  other. 
The  gasoline  in  tank  No.  2  will  therefore  be  always  under  the 
same  pressure  and  when  the  lamps  are  once  burning  the  gasoline 
supply  to  each  lamp  will  be  a  constant  amount. 

Tank  No.  2  is  separated  by  the  head  13  into  two  compartments, 
marked  18  and  19.  The  connection  between  the  two  compart- 
ments is  made  by  the  valve  15  and  the  connection  16.  The 
gasoline  supply  for  the  lighting  system  is  taken  from  the  lower 
chamber  at  the  valve  marked  17. 

It.  is  possible  to  refill  this  tank  with  gasoline  while  the  system 
is  working.  To  accomplish  this,  the  air  supply  is  cut  off  from 
tank  No.  1,  by  closing  valve  9  and  the  valve  15  is  closed  to  retain 
the  pressure  on  the  lower  chamber  of  tank  No.  2.  The  screw- 
plug  is  then  taken  from  the  tube  12  and  the  tank  refilled.  The 
screw-plug  is  then  returned  to  its  place,  the  valves  9  and  15  are 
again  opened  and  the  regulating  valve,  immediately  restores  the 
desired  pressure. 

The  amount  of  pressure  required  on  the  system  will  depend  on 
the  height  to  which  the  gasoline  is  carried  within  the  building. 
The  pressure  is  generally  1  pound  to  each  foot  in  height  and  to 
do  the  best  work  the  pressure  must  be  constant. 

18 


274  MECHANICS  OF  THE  HOUSEHOLD 

These  plants  may  serve  as  a  fuel  supply  for  gasoline  stove  as 
indicated  at  R  or  any  other  source  of  domestic  heating.  The 
usual  gravity  supply  tank  is  replaced  by  the  hollow  wire  through 
which  is  the  gasoline  from  the  tank  in  the  basement. 

Mantle  Gas  Lamps. — Mantle  lamps  that  are  intended  for 
using  city  gas  are  much  the  same  in  construction  as  those  using 
the  cold-process  gasoline  gas;  the  styles  of  mechanism  differ 
somewhat  with  manufacturers  but  all  lamps  of  this  kind  possess 
the  essential  features  that  are  common  to  all.  Either  of  these 
gases  may  be  used  with  open-flame  burners,  such  as  Fig.  193,  but 
since  the  introduction  of  mantle  lamps,  the  open-flame  burners 
are  rarely  used  for  household  illumination. 

In  the  incandescent-mantle  lamp,  the  light  is  produced  by 
heating  to  incandescence  a  filmy  mantle  of  highly  refractory 
material.  The  higher  the  temperature  to  which  the  mantle  of 
a  lamp  is  raised, 'the  greater  is  the  quantity  of  light  produced. 
The  office  of  the  burner  is  to  produce  a  uniform  heat  throughout 
the  mantle  with  the  use  of  the  least  amount  of  gas.  As  ordinarily 
furnished  from  the  mains,  coal  gas  or  gasoline  gas  is  too  rich  in 
carbon  to  be  used  in  mantle  lamps  without  dilution.  When  gas 
is  burned  in  a  mantle  lamp,  it  must  contain  sufficient  oxygen — 
which  is  supplied  by  the  air — to  combine  completely  with  the 
contained  carbon  and  reduce  it  to  carbon  dioxide.  If  insufficient 
air  is  supplied,  the  lamp  will  smoke  and  the  mantle  will  soon  be 
filled  with  soot. 

In  the  use  of  the  various  gases — made  from  coal,  gasoline, 
kerosene,  alcohol,  etc. — as  a  fuel  for  the  production  of  either 
heat  or  light,  the  form  of  the  burner  in  which  the  gas  is  consumed 
is  the  most  important  factor  of  the  system.  Without  burners 
in  which  to  generate  a  satisfactory  supply  of  heat  for  the  desired 
purposes,  mantle  gas  lamps  would  never  have  come  into  common 
use.  An  understanding  of  the  mechanism  of  the  burners  of  a 
system  is  of  first  importance  because  of  the  possibility  of  the 
failure  of  the  entire  plant  through  an  improper  adjustment  of 
the  lamps. 

If  complete  combustion  of  the  gas  is  attained  in  the  burner, 
the  greatest  amount  of  heat  will  be  evolved  and  the  residue 
will  be  an  odorless  gas,  carbon  dioxide  (C02).  If  the  gas  is  not 


GASEOUS  AND  LIQUID  FUELS 


275 


E 


completely  burned  the  odor  of  the  gas  is  noticeable  in  the  air. 
Incomplete  combustion  may  be  caused  by  an  insufficient  air 
supply,  which  causes  a  smoky  flame;  or  if  a  larger  flame  is  used 
than  the  burner  is  designed  to  carry,  some  of  the  gas  will  escape 
unburned.  In  either  case  the  greatest  amount  of  heat  is  not 
developed  by  the  burner. 

In  most  burners,  whether  for  heating  or  lighting — in  which 
gas,  gasoline  or  alcohol  is  used  as  a  fuel — the  principle  of  operation 
is  that  of  the  Bunsen  tube.  One  noticeable  exception  to  this 
rule  is  the  burners  used  with  the  central- 
generating  systems  where  the  Bunsen  tube  is 
a  part  of  the  generator. 

The  gas  generated  from  any  hydrocarbon 
will  burn  completely,  only  after  being  mixed 
with  air  or  other  incombustible  gas,  in  pro- 
portions such  as  will  completely  oxidize  the 
carbon  contained  in  the  fuel. 

In  Fig.  190  the  familiar  laboratory  Bunsen 
burner  affords  an  excellent  illustration  of 
the  Bunsen  principle  which  forms  a  part  of 
all  burners  using  gas  as  a  fuel.  The  gas  from 
the  supply  pipe  issues  from  a  small  opening 
A  into  a  tube  B  and  by  the  force  of  its  veloc- 
ity the  entering  gas  carries  into  the  tube 
above  it  a  quantity  of  air  that  may  be  reg- 
ulated by  the  size  of  the  opening.  If  the 
gas  is  burned  without  being  first  mixed  with 
air,  the  flame  will  be  dull  and  smoky  but  if  air  is  admitted  to 
mix  with  the  gas,  an  entirely  different  flame  is  produced,  the 
characteristic  shape  of  which  is  shown  in  the  figure. 

The  upper  part  of  the  flame  C  is  known  as  the  reducing  flame; 
it  is  blue  in  color  and  intensely  hot.  The  portion  D  is  the  oxidiz- 
ing flame;  it  is  pale  blue,  sometimes  light  green  in  color.  The 
lower  part  E  is  the  gas  before  it  begins  to  burn.  When  burning 
in  air,  the  Bunsen  flame  gives  scarcely  any  light,  all  of  the  energy 
being  expended  in  heat.  In  the  gas  stove  where  the  burners 
are  made  up  of  a  great  number  of  small  jets,  it  will  be  seen  that 
each  jet  shows  the  characteristic  features  of  the  Bunsen  flame. 

The  incandescent-mantle  gaslight  takes  advantage  of  the  heat 


FIG.  19  0. — Cross- 
section  of  Bunsen  bur- 
ner showing  character- 
istic Bunsen  flame. 


c 


276  MECHANICS  OF  THE  HOUSEHOLD 

generated  by  the  Bunsen  flame  and  produces  an  incandescent 
light  that  has  revolutionized  gas  lighting.  The  flame  of  the 
Bunsen  tube  is  burned  inside  a  mantle  which  is  rendered  in- 
candescent by  the  heat. 

The  incandescent  mantle  was  invented  by  Dr.  Auer  von 
Welsbach  and  was  known  for  a  long  time  as  the  Welsbach  light ; 
but  improvements  in  the  process  of  making  the  mantles,  brought 
other  lamps  of  the  same  type  on  the  market,  when  it  became 
known  as  the  mantle  lamp.  The  first  serviceable  mantles  were 
made  in  1891  and  from  that  time  there  has  been  a 
steady  development  in  the  gas-lighting  industry. 

The  original  mantles  were  made  of  knitted  cotton 
yarn,  impregnated  with  rare  earths  and  are  still  so 
made;  but  the  most  durable  mantles  are  now  con- 
structed from  ramie  or  china  grass.  After  being 
knitted,  the  mantles  are  impregnated  with  thorium 
nitrate,  with  the  addition  of  a  small  quantity  of 
cerium  nitrate,  and  occasionally  other  nitrates. 
The  mantles  are  then  shaped  and  mounted;  the  fiber 
is  burned  out  and  the  mantles  are  dipped  in  collo- 
dion to  give  them  stability  for  transportation.  When 
placed  in  the  lamp  for  use,  the  collodion  is  first 
burned  off  and  the  remaining  oxide  of  thorium  forms 

FlG  IQI the  incandescent  mantle.     One  style  of  mantle  is 

Gas  lamp  now  being  made  in  which  the  fiber  is  not  burned  out 
mantle!Pn*  until  it  is  placed  in  the  lamp.  They  are  commonly 
used  with  gasoline  lamps  and  give  very  good  results. 
The  first  incandescent-mantle  gas  lamps  to  be'  used  were  of 
the  upright  type,  such  as  is  shown  in  Fig.  191,  and  for  a  long 
time  they  were  the  only  mantle  lamps  in  use.  While  the  upright 
mantle  was  a  great  improvement  over  the  open-flame  gas  jet, 
the  lamp  was  not  satisfactory  because  of  the  shadows  cast  by 
the  fixture  and  from  the  fact  that  a  large  amount  of  the  light  was 
lost  by  being  directed  upward  from  the  incandescent  mantle. 

With  the  development  of  the  inverted  type,  the  mantle  lamp 
was  greatly  improved.  In  the  use  of  lamps  of  any  kind,  the 
desired  position  of  the  illumination  is  that  in  which  the  light  is 
directed  downward.  In  the  inverted  type  of  mantle  lamp  this 
feature  is  accomplished  and  adds  materially  to  the  efficiency  of 


GASEOUS  AND  LIQUID  FUELS 


277 


the  light,  because  the  rays  are  sent  in  the  direction  of  greatest 
service.  The  upright  mantle  lamps  are  still  sold  but  by  far  the 
greater  number  offered  for  sale  are  of  the  inverted  type. 

The  essential  features  of  all  gas  lamps  used  under  these  con- 
ditions are  shown  in  Fig.  192,  which  represents  the  common 
bracket  type  of  lamp.  The  gas-cock  C,  connects  the  lamp  with 
the  gas  supply  G.  The  gas  escapes  into  the  Bunsen  tube,  through 
an  opening  in  the  tip  P,  which  is  so  constructed  that  the  amount 
of  gas  may  be  varied  to  suit  the  required  conditions.  The 
brass  screw  nut  N  may  be  raised  or  lowered  and  thus  increase  or 
diminish  the  amount  of  escaping  gas  by  reason  of  the  position 
of  the  pin  P.  If  the  nut  is  screwed  completely  down  the  pin 
closes  the  opening  and  the  gas  is  entirely  shut  off.  When  the 
lamp  is  put  in  place,  the  burner 
is  adjusted  to  admit  the  proper 
amount  of  gas  and  so  long  as  the 
quality  of  the  gas  remains  the 
same,  no  further  adjustment  will 
be  necessary.  Any  change  to  a 
richer  or  poorer  gas  will,  however, 
require  an  adjustment  of  the 
burner  to  suit  the  mantle.  The 
amount  of  gas  admitted  is  only 
that  which  will  produce  complete 

combustion  in  the  mantle  when  combined  with  the  required 
amount  of  air.  Each  burner  must,  therefore,  be  designed  for 
the  mantle  in  use. 

As  the  gas  leaves  the  opening  above  the  pin  P,  it  enters  the 
mixing  chamber  of  the  Bunsen  tube  and  air  is  drawn  at  the 
openings  A-A.  The  mixture  of  the  gas  and  air  is  accomplished 
in  the  tube  leading  to  the  mantle  M,  where  it  is  burned.  In 
all  lamps  of  this  kind,  there  is  a  wire  screen  placed  relatively  as 
S,  the  object  of  which  is  to  prevent  the  mixture  in  the  tube  from 
exploding— in  case  of  low  pressure— and  thus  cause  the  gas  to 
ignite  and  burn  at  the  point  of  entrance  to  the  tube. 

At  any  time  the  pressure  is  insufficient  to  send  a  steady  flow 
of  gas  into  the  tube,  the  flame  may  " flash  back"  and  ignite  the 
gas  at  the  point  of  entrance  where  it  will  continue  to  burn.  If. 


FIG.  192. — Mantle  gas  lamp  show- 
ing details  of  Bunsen  tube. 


278  MECHANICS  OF  THE  HOUSEHOLD 

however,  the  screen  is  interposed  between  the  gas  supply  and  the 
burner,  the  flame  of  explosion  will  not  pass  the  screen. 

In  lighting  the  lamp,  the  gas  is  turned  on  and  a  lighted  match 
is  held  under  the  mantle,  the  explosive  mixture  of  gas  and  air 
fills  the  mantle  and  escapes  into  the  globe,  in  which  it  is  usually 
inclosed.  As  soon  as  ignition  takes  place  the  gas  outside  the 
mantle  explodes  with  the  effect  that  is  startling  but  not  necessarily 
dangerous.  The  escaping  gas  continues  to  burn  and  heats  the 
mantle  to  incandescence. 

The  amount  of  escaping  gas  is  regulated  by  turning  the  gas- 
cock  to  produce  the  greatest  brilliance  with  the  least  flame  out- 
side the  mantle.  When  used  for  household  illumination,  the 
intensity  of  the  light  is  such  as  to  be  objectionable,  when  used 
directly;  but  when  surrounded  by  an  opal  glass  globe  to  diffuse 
the  light,  this  is  a  highly  satisfactory  and  economical  means  of 
lighting. 

Open-flame  Gas  Burners. — Gas  jets  of  the  open-flame  type 
continue  to  be  used  to  some  extent  but  the  more  efficient  mantle 

lamp  has  very  largely  supplanted 
lights  of  this  kind.  In  the  past, 
these  gas  lights  were  made  in  a 
great  many  styles  and  were 
known  under  a  variety  of  trade 
names — the  fish-tail  burner,  the 
bats-wing  burner  and  the  Ar- 
gand  burner — and  were  at  times 
F,G.  :93.-Swmg-bracketEriamp  very  generally  used  for  gas 

with  open-flame  burner.  lighting. 

The  common  gas  jet  is  illus- 
trated in  Fig.  193.  The  figure  shows  a  bracket  fixture  which 
is  generally  fastened  to  a  pipe  in  the  wall.  A  swing-joint  at  A 
permits  the  flame  F  to  be  moved  into  different  positions.  The 
annular  opening  A  permits  the  gas*  to  pass  to  the  jet  in  any 
position  to  which  the  light  is  moved.  The  gas-cock  C  is  a  cone- 
shaped  plug,  which  has  been  ground  to  perfectly  fit  its  socket. 
It  should  move  with  perfect  freedom,  and  yet  prevent  the  es- 
cape of  the  gas.  A  slotted  screw  N  permits  the  joint  to  be  re- 
adjusted, should  the  plug  become  loose  in  the  socket. 

The  gas-tips   T  are  made  of  a  number  of  different  kinds  of 


GASEOUS  AND  LIQUID  FUELS 


279 


materials  and  are  commonly  termed  lava-tips  but  tips  for  gas 
and  gasoline  are  frequently  made  of  metal.  The  bottom  of  the 
tip  is  cone-shaped,  which  permits  it  to  be  forced  into  place  in  the 
end  of  the  tube  with  a  pair  of  pliers.  In  size  the  tips  are  graded 
by  the  amount  of  gas  which  they  will  allow  to  escape  in  cubic 
feet  per  hour.  For  example — a  4-foot  tip  will  use  approximately 
4  cubic  feet  of  gas  per  hour.  They  are  made  in  a  number  of  sizes 
to  suit  the  varying  requirements. 

The  Inverted-mantel  Gasoline  Lamp. — The  inverted-mantle 
gasoline-gas  lamp  shown  in  Fig.  194,  furnishes  a  good  example  of 
mechanism  and  principle  of  operation,  when  used  with  the  hollow- 
wire  system.  This  is  the  bracket  style  of  lamp  but  the  same 
mechanism  is  used  in  other  forms  of  fixtures.  Lamps  of  similar 


FIG.   194.- — Sectional  view  of  hollow-wire  mantle  gasoline  lamp. 

construction  are  suspended  from  the  ceiling,  either  singly  or  in 
clusters;  they  are  also  used  in  portable  form. 

In  Fig.  194  the  lamp  consists  of  a  bracket  H,  which  is  secured 
to  the  wall  and  through  the  stem  of  which  the  gasoline  is  con- 
ducted to  the  generator  by  the  pipe  W .  The  arrows  show  the 
course  of  the  gasoline  and  its  vapor  as  it  passes  through  the  lamp. 
On  entering  the  generator  the  gasoline  first  passes,  the  percola- 
tion, through  an  asbestos  wick  B,  the  object  of  which  is  to  pre- 
vent the  vapor  pressure  from  acting  directly  on  the  gasoline  in 
the  supply  tube.  The  gasoline  passes  through  the  wick  B, 
largely  by  capillary  action,  as  it  must  enter  the  generator  against 
a  pressure  greater  than  that  afforded  by  the  pressure  tank.  The 


280  MECHANICS  OF  THE  HOUSEHOLD 

vaporization  of  the  gasoline  takes  place  in  the  tube  above  the 
mantle  T,  from  the  flame  of  which  it  receives  the  necessary  heat. 

In  lighting  the  lamp  an  asbestos  torch  saturated  with  alcohol  is 
ignited  and  hung  on  the  frame,  so  that  the  flame  may  heat  the 
generating  casting  N.  This  process  usually  requires  less  than  a 
minute,  generally  about  40  or  50  seconds.  The  torch  supplies 
heat  sufficient  to  generate  the  vapor  for  lighting  the  lamp,  but 
as  soon  as  lighted  the  heat  from  the  glowing  mantle  keeps  the 
generator  at  the  required  temperature  for  continuous  supply  of 
vapor. 

When  the  generator  is  sufficiently  heated  by  the  generating 
torch,  the  needle  valve  N  is  opened  by  pulling  the  chain  P.  This 
allows  the  gasoline  vapor  from  the  generating  tube  to  escape  at 
G  into  the  induction  tube  R.  As  the  vapor  enters  the  induction 
tube  at  a  high  velocity,  it  carries  with  it  the  atmospheric  air  in 
quantity  sufficient  to  render  it  completely  combustible.  The 
opening  G  and  the  tube  together  form  a  Bunsen  burner.  The 
lamp  is  so  proportioned  as  to  give  a  mixture  of  gasoline  vapor  and 
air  that  will  produce  complete  combustion  in  the  mantle  T.  The 
portion  of  the  burner  Z,  through  which  the  gas  enters  the  mantle, 
is  a  brass  tip,  filled  with  a  fluted  strip  of  German  silver,  so  ar- 
ranged that  the  gas  on  entering  the  mantle  will  be  uniformly 
distributed  and  that  the  heat  generated  will  render  the  entire 
mantle  uniformly  brilliant. 

One  feature  of  the  lamp  that  requires  special  attention  is  the 
opening  G,  through  which  the  vapor  from  the  generator  is  dis- 
charged into  the  induction  tube.  This  is  a  very  small  opening 
and  occasionally  becomes  stopped  or  partly  closed.  When  this 
occurs  the  lamp  fails  to  receive  the  necessary  amount  of  gas, 
and  the  light  is  unsatisfactory.  In  this  lamp,  the  cleaning 
needle  Q  is  provided  for  removing  the  stoppage.  The  needle 
is  simply  screwed  into  the  opening  and  forces  out  the  obstruc- 
tion; when  it  is  withdrawn,  the  opening  is  left  free.  A  more 
convenient  device  for  accomplishing  the  same  purpose  is  de- 
scribed in  the  portable  lamp,  Figs.  195  and  196. 

Portable  Gasoline  Lamps. — The  portable  form  of  desk  and 
reading  lamps  for  the  use  of  gasoline  is  made  in  a  great  variety 
of  styles.  They  are  sometimes  constructed  to  feed  by  gravity, 
but  by  far  the  greater  number  are  operated  by  the  pressure 


GASEOUS  AND  LIQUID  FUELS  281 

method.  The  portable  lamp  must  be  a  complete  gas  plant, 
with  storage  tank  for  the  gasoline,  pipe  system  for  conducting  the 
gasoline  to  the  lamp,  generator  and  burner.  To  give  satis- 
factory results,  the  lamp  must  be  capable  of  being  lighted  with 
the  least  degree  of  trouble  and  operated  with  the  least  amount 
of  care.  The  immense  number  of  lamps  of  this  kind  that  are 
sold  shows  that  they  meet  all  of  these  requirements  and  have 
proven  satisfactory  in  operation.  Their  greatest  attractiveness 
is  their  capability  of  giving  a  very  large  amount  of  light  at 
relatively  low  cost. 

Fig.  195  illustrates  a  portable  gasoline  lamp  in  which  a  con- 
venient and  efficient  form  of  generating  mechanism  is  combined 
with  an  attractively  proportioned  exterior.  The 
lamp  works  on  the  principle  of  the  hollow-wire 
system,  the  base  serving  as  a  storage  and  pressure 
tank,  the  frame  of  the  lamp  acting  as  the  tube  for  D- 
supplying  the  lamp  with  gasoline,  and  the  canopy 
containing  the  generating  mechanism. 

The  tank  in  the  base  is  filled  with  gasoline  at 
the  opening  E,  which  is  made  air-tight  by  a  screw- 
plug.     The  plug  also  contains  an  attachment  piece     E 
for  the  air  pump,  which  furnishes  the  pressure  to 
the  gasoline.     The  hollow  standard  reaches  to  the 
bottom  of  the  tank  and  through  it  the  gasoline      FIQ     195_ 
is  forced  to  the  point  marked  A,  where  the  gaso-  Portable,  gaso- 
line enters  the  generating  mechanism.     This  part  j*£®  mantl 
of  the  lamp,  which  is  entirely  concealed  by  the 
lamp  canopy,  is  shown  in  detail  in  Fig.    196.     The  reference 
letters  in  Fig.  195  apply  to  the  same  parts  in  the  detail  drawing. 

The  gasoline  enters  an  asbestos-packed  tube  F  at  the  point  A, 
and  after  percolating  trough  the  tube,  reaches  the  regulating 
valve  at  the  point  G.  The  hand-wheel  B  opens  and  closes  the 
valve,  and  thus  controls  the  entrance  of  the  gasoline  to  the  gen- 
erating tube  H,  where  it  is  converted  into  the  vapor.  The  vapor 
now  needs  only  the  addition  of  air  to  make  it  the  desired  gas  for 
illuminating  the  mantle.. 

The  vapor  from  the  generating  tube  escapes  at  the  small  hole 
K ,  located  directly  under  the  mixing  chamber  M .  The  supply  of 
air  is  received  through  the  tube  (7,  provided  with  a  regulator, 


282 


MECHANICS  OF  THE  HOUSEHOLD 


which  is  readily  accessible  from  the  outside  of  the  lamp.  The 
mixture  of  gasoline  vapor  and  air  is  accomplished  as  in  the  other 
lamps  described,  through  the  Bunsen  tube  N.  In  this  case,  the 
Bunsen  tube  is  extended  and  increased  in  size  to  produce  a 
mixing  chamber  of  considerable  volume.  The  mantle  is  attached 
to  the  tip  0.  The  tip,  like  the  one  already  described,  is  made 
of  German  silver  and  constructed  to  produce  a  flame  that  will 
entirely  fill  the  mantle. 

This  lamp  is  provided  with  a  special  means  of  keeping  the 
opening  K  free  from  accumulations.     The  opening  K,  through 

which  the  gasoline  vapor  es- 
capes from  the  generator,  is  very 
small  and  a  slight  stoppage  will 
materially  interfere  with  the  flow 
of  the  vapor  and  thus  impair 
the  illuminating  effect  of  the 
light.  A  lever  D  operates  an 
eccentric  which  engages  the 
piece  P,  to  which  is  attached  a 
pin  that  readily  enters  an  open- 
ing K,  when  the  lever  is  turned. 
Any  accumulation  which  may 
lodge  in  the  opening  is  instantly 
removed  and  the  needle  re- 
turned to  its  place  by  a  turn  of 
the  lever  D. 

Central -generator  Plants.— 
The  central-generator  or  tube 
system  of  lighting  with  gasoline, 
differs  from  the  other  methods 
described,  in  the  manner  of 
generating  and  distributing  the 
In  the  hollow-wire  system  each 
lamp  generates  its  own  gas  supply.  With  the  central-generator 
system  the  gas  for  all  of  the  lamps  is  generated  and  properly 
mixed  with  air  in  a  central  generator,  and  the  finished  gas  dis- 
tributed through  tubes  to  the  different  burners  and  there  burned 
in  incandescent  mantles.  The  gas  as  it  leaves  the  generator 


FIG.  196. — Sectional  view  of  the 
generator  for  the  American  hollow- 
wire  gasoline  lamp. 

supply  of  gas  to  the  lamps. 


GASEOUS  AND  LIQUID  FUELS  283 

requires  no  further  mixing  with  air  and  therefore  the  burners  are 
not  of  the  Bunsen  type. 

Central-generator  gas  machines  are  made  in  a  number  of 
different  forms  by  different  manufacturers,  all  of  which  are 
intended  to  perform  the  same  work  but  differ  in  the  mechanism 
employed.  The  machines  are  simple  in  construction  and  as  in 
the  hollow-wire  system  are  capable  of  using  lower  grades  of 
gasoline  than  can  be  used  with  the  cold-process  plants.  The 
gas  from  a  central  generator  may  be  used  for  all  purposes  for 
which  gasoline  gas  is  employed,  either  for  lighting  or  heating. 
One  difficulty  in  the  use  of  the  machine  is  the  lack  of  flexibility 
when  required  for  only  a  few  lamps  or  varying  number  of  lights. 
Although  these  plants  are  sometimes  used  for  lighting  and  heat- 
ing dwellings,  their  use  is  limited,  for  the  reason  that  variation 
of  the  number  of  lights  requires  the  generator  to  be  regulated 
to  suit  the  change  in  the  gas  supply.  The  plants  cannot  be 
conveniently  cut  down  to  one  light.  Their  most  general  use  is 
that  of  lighting  churches,  stores,  halls,  auditoriums,  etc.,  where 
a  variable  amount  of  light  is  not  demanded.  Plants  of  this 
character  are  quite  generally  used  for  street  lighting  and  for 
other  outside  illumination. 

An  efficient  and  simple  plant  of  the  central-generator  type  is 
shown  in  Fig.  197.  The  supply  of  gasoline  is  stored  in  a  tank 
similar  to  that  used  with  the  hollow- wire  system  and  placed  in 
any  convenient  location.  The  gasoline  is  conducted  to  the  gen- 
erator G,  through  a  hollow  wire  marked  W.  The  generator  is 
inclosed  in  a  sheet-iron  box,  which  is  located  at  any  convenient 
place  in  the  building.  From  the  generator  the  gas  is  conducted 
through  the  tube  to  the  lamps  L. 

In  Fig.  198  is  shown  a  diagram  of  the  generator,  cut  through 
the  middle  lengthwise,  in  which  all  of  the  working  parts  are 
shown  in  their  relative  positions.  The  reference  figures  designate 
the  same  parts  of  the  generator  in  Figs.  197  and  198. 

In  the  process  of  generation  the  tank  is  filled  with  gasoline 
and  pressure  applied  with  the  air  pump.  The  tanks  described 
in  Fig.  189  might  be  used  to  advantage  with  this  plant  but  the 
one  shown  in  Fig.  197  is  so  constructed  that  the  larger  tank  is 
used  for  storage  of  gasoline.  The  gasoline  is  pumped  directly 
into  the  smaller  tank  which  alone  is  kept  under  pressure.  The 


284 


MECHANICS  OF  THE  HOUSEHOLD 


pump  P  is  enclosed  in  the  large  tank;  at  any  time  it  is  desired  to 
replenish  the  supply  of  gasoline,  it  is  only  necessary  to  open  the 
valve  V  and  pump  the  necessary  supply  into  the  small  tank. 
This  transfer  may  be  done  at  any  time  without  danger  from 
escaping  gasoline  vapor. 

The  process  of  generating  the  gas  is  best  understood  by  ref- 
erence to  Fig.  198,  which  shows  the  internal  construction  of  the 


FIG.  197. — Diagram  of  central-generator  tube  system  of  gasoline  lighting. 


generator.  The  liquid  gasoline  is  admitted  at  the  bottom 
through  the  small  pipe  W,  and  then  enters  the  space  4,  where  it 
is  vaporized.  The  initial  flow  of  gas  is  generated  by  heating 
the  .generator  with  an  alcohol  flame  from  the  iron  cup  1,  which 
surrounds  the  generator.  When  the  generator  is  heated  the 
gasoline  admitted  to  the  generator  is  immediately  vaporized; 
when,  by  turning  the  handle  6,  the  needle  valve  5  opens  a  small 


GASEOUS  AND  LIQUID  FUELS 


285 


orifice  through  which  the  heated  gasoline  vapor  escapes  into  the 
tube  7,  above. 

The  blast  of  vapor  issuing  from  the  orifice  carries  with  it  air 
of  sufficient  volume  to  render  the  gasoline  vapor  an  explosive 
mixture  that  when  burned  in  the  mantle  will  be  reduced  to 
C02  gas. 

When  the  initial  heating  by  the  alcohol  flame  is  exhausted, 
sufficient  gas  has  been  generated  so  that  part  of  it  may  be  used 
as  a  sub-flame  in  the  gas  burner  9, 
to  keep  the  generator  heated.  The 
gas  is  conducted  to  the  burner 
from  the  main  tube  11,  through 
the  pipe  12-14,  as  indicated  by  the 
arrows.  The  burner  9  surrounds 
the  generator  and  the  size  of  the 
flame  is  regulated  by  the  valve  15, 
which  is  opened  an  amount  suffi- 
cient to  admit  the  necessary  gas 
to  the  burner. 

To  start  the  generator,  the  cup 
1  is  filled  with  alcohol  and  ignited. 
The  needle  valve  2  is  now  opened 
by  turning  the  hand-wheel  3,  ad- 
mitting gasoline  into  the  generator 
chamber  4,  where  the  vaporization 
of  the  gasoline  takes  place.  The 
flame  from  the  burning  alcohol  will 
heat  the  generator  in  about  a  minute.  When  the  generator  is 
hot,  the  needle  valve  5  is  opened  slightly,  by  turning  the  lever 
6,  and  the  gasoline  vapor  under  high  pressure  blows  into  the 
tube  7.  As  the  gasoline  vapor  is  blown  into  the  tube  7,  air  is 
drawn  in  through  the  opening  8,  as  indicated  by  the  arrows. 
The  generator  is  practically  a  large  Bunsen  tube  from  which 
the  mixture  of  gasoline  vapor  and  air  is  conducted  to  the  burners 
by  a  connecting  pipe. 

Gas  machines  operated  on  this  principle  are  made  to  accom- 
modate a  definite  number  of  lamps.  After  the  lamps  are  lighted, 
the  amount  of  gas  is  regulated  to  suit  the  number  in  use.  If  at 
any  time  it  is  desired  to  reduce  the  number  of  lamps  in  opera- 


Gasoline 


FIG.  198. — Cross-section  of  the 
generator  for  the  tube  system  of 
gasoline  lighting. 


286  MECHANICS  OF  THE  HOUSEHOLD 

tion,  the  gas  supply  must  be  regulated  to  suit  the  lights  left 
burning. 

As  an  illustration,  suppose  that  a  plant  of  ten  lamps  had  been 
burning  and  that  it  was  desired  to  reduce  the  number  to  six; 
four  of  the  lamps  are  extinguished  by  turning  the  levers  C,  which 
control  the  gas-cocks.  The  generator  which  had  been  supplying 
sufficient  gas  for  ten  lights  will  continue  to  produce  the  same 
amount  until  the  lever  6  is  turned  to  reduce  the  supply  of  gasoline 
to  the  required  amount  for  six  lamps.  This  is  done  by  gradually 
closing  the  valve  5  until  the  lamps  again  burn  brightly. 

In  small  plants  the  least  number  of  lamps  that  will  work 
satisfactorily  at  one  time  is  three.  Automatic  regulators  are 

made  for  plants  of  consider- 
able size  but  do  not  satisfac- 
torily control  the  gas  when  the 
lamps  are  reduced  below  three 
in  number.  The  gas  from  these 
plants  may  readily  be  used  in 
kitchen  ranges,  water  heaters 
and  other  domestic  purposes. 
Individual  plants  for  operating 
ranges  in  restaurants  and  hotels 
are  in  common  use.  The  plants 
FIG.  199.— Gas  lamp  for  use  with  the  are  subject  to  minor  derange- 

central-generator  or  tube  system  of  gaso-  ,,  .  ,• 

line  lighting.  ments  that  require  correcting  as 

they  occur,  but  as  soon  as  the 

mechanism  and  characteristic  properties  of  the  plant  are  known, 
the  correction  of  any  difficulty  that  may  present  itself  is  easily 
accomplished. 

Central-generator  Gas  Lamps.— Fig.  199  shows  the  general 
construction  and  arrangement  of  the  parts  of  the  inverted- 
mantle-lamp  used  with  the  central-generator  system.  In  out- 
ward appearance  the  lamp  is  much  like  any  other  inverted-mantle 
gas  lamp,  but  in  arrangement  of  parts  it  is  markedly  different. 
The  gas-cock  C  is  larger  than  that  used  with  the  ordinary  fixture, 
because  the  opening  0  must  carry  a  larger  volume  of  gas  than 
that  for  supplying  gas  to  lamps  using  the  Bunsen  tube.  In 
the  use  of  lamps  with  the  Bunsen  tube,  the  gas  from  the  mains 
is  mixed  with  approximately  twenty  times  its  volume  of  air; 


GASEOUS  AND  LIQUID  FUELS 


287 


with  a  lamp  like  that  of  Fig.  199,  where  the  mixture  has  already 
been  made  in  the  generator,  the  conducting  tubes  and  the  gas- 
cock  must  be  relatively  very  large. 

The  screen  S,  which  corresponds  to  the  screen 
S  in  Fig.  192,  is  quite  as  necessary  as  in  the  other 
lamp.  It  not  only  assures  a  uniform  distribution 
of  the  gas  in  the  tube  but  it  prevents  the  mantle 
from  being  broken  when  the  burner  is  lighted. 
If  this  screen  is  punctured,  the  explosion  which 
takes  place  when  the  burner  is  lighted  will  be 
sufficient  to  blow  out  the  bottom  of  the  mantle. 
The  burner  tip  T  is  practically  the  same  as  that 
used  with  other  mantle  lamps. 

Boulevard    Lamps. — Gasoline 
lamps  for  outside  illumination  may 
be  constructed  to  operate  with  any 
of  th,e  systems  described,  but  the 
hollow-wire     and     the     generator 
systems  are  most  conveniently  used, 
because  each  post  may  be  arranged  jjjj^0^ 
as  an  independent  plant.     For  illu-  with 
minating  private  grounds  or  public 
thoroughfares,    lamps  such  as  are 
illustrated  in  Figs.  200  and  201  are  very  generally 
used. 

The  lamp  shown  in  Fig.  200  is  of  the  central 
generator  type  in  which  the  storage  tank  and 
generator  mechanism  are  located  in  the  base  of 
the  post.  These  lamps  are  also  sometimes  con- 
structed with  a  time  attachment  in  the  base  of  the 
post,  arranged  with  a  clock  mechanism  so  that 
the  light  may  be  automatically  extinguished  at 


generator 


FIG.  201.—  any  desired  time. 

Boulevard  lamp  jn  Fig>  201  the  lamp  is  of  the  hollow-wire  type 
h^iut*wi?e  and  as  in  the  case  of  the  other,  the  supply  tank 
method  of  light-  fs  m  the  base  of  the  post.  With  this  system 
it  would  be  possible  to  supply  several  lamps  from 
a  common  supply  tank,  provided  the  hollow  wire  was  protected 
against  damage.  The  lamps  arranged  to  work  on  either  system, 


288 


MECHANICS  OF  THE  HOUSEHOLD 


require  the  same  amount  of  attention  and  are  subject  to  the 
same  derangements  as  those  for  inside  service. 

Burners  for  gasoline  stoves  are  made  in  a  great  variety  of 
forms,  each  having  some  special  points  of  excellence  that  are 
used  to  recommend  the  sale  of  the  stove.  The  most  essential 
feature  of  a  gasoline  stove  is  the  burner,  since  on  its  successful 
performance  will  depend  the  satisfaction  given  by  the  stove. 
Many  self -generating  burners  have  been  devised  which  have  met 
with  a  great  deal  of  favor,  but  the  type  of  burner  most  widely 

used  and  the  first  to  be  de- 
vised  for  the  purpose  is  the 
generating  burner  similar  in 
principle  to  the  generating 
gasoline  lamp. 
•  The  burner  is  first  heated 
from  an  outside  source,  in 
order  to  generate  sufficient 
gas  to  start  the  flame,  after 
which  the  heat  from  the 
burner  will  develop  the  gas 
supply.  With  gasoline  stoves 
of  this  kind,  the  supply  tank 
is  elevated,  in  order  that  the 
force  of  gravity  may  give 
sufficient  pressure  to  send 
FIG.  202.— Sectional  view  of  the  generator  the  gasoline  into  the  genera- 

and  burner  of  a  gasoline  stove.  ^or  wnile  the  flame  is    burn- 

ing.      In    the    hollow- wire 

system  the  same  type  of  burner  is  used,  but  the  gasoline  is  forced 
into  the  burner  by  the  pressure  in  the  tank. 

In  Fig.  202  is  shown  a  sectional  view  of  the  burner  as  it  appears 
in  the  stove.  The  supply  tank,  or  hollow  wire  from  the  pressure 
tank,  sends  the  gasoline  into  the  tube  A  at  the  bottom  of  the 
stove,  to  which  several  burners  may  be  attached.  The  tube  B, 
through  which  the  gasoline  percolates  on  its  way  to  the  generator, 
is  filled  with  moderately  coarse  sand,  or  other  material  that  is 
intended  to  prevent  the  gasoline  from  being  forced  out  of  the 
pipe  by  the  pressure  that  is  developed  in  the  generator.  The 


GASEOUS  AND  LIQUID  FUELS  280 

pieces  C-C  are  perforated  metal  plugs  that  prevent  the  escape 
of  the  particles  of  which  B  is  composed. 

The  generator  is  a  brass  casting  D-D  which  is  firmly  screwed 
to  the  top  of  the  tube  B.  A  needle-valve  E  governs  the  discharge 
of  the  gasoline  vapor  at  G,  where  the  vapor  enters  the  tube  H ,  as 
indicated  at  K-K.  The  gasoline  vapor  enters  the  open  Bunsen 
tube  H,  and  with  it  is  carried  the  air  necessary  to  produce  the 
required  gas  for  complete  combustion.  The  piece  N  is  the 
generating  cup  in  which  is  burned  the  generating  fluid — either 
gasoline  or  alcohol.  The  gasoline  from  the  pipe  A  percolates 
through  the  material  in  B  and  flows  into  the  generator.  The 
needle-valve  being  closed,  the  space  D-D  fills  with  gasoline. 

To  light  the  burner,  the  hand-wheel  /  is  turned,  opening  the 
needle-valve  a  sufficient  length  of  time  to  allow  the  gasoline  to 
fill  the  cup  N  with  fuel  for  generating  the  initial  volume  of  vapor. 
A  still  better  way  is  to  fill  the  cup  with  alcohol,  because  the  burn- 
ing alcohol  does  not  fill  the  air  with  smoke  and  odors,  as  in  the 
case  of  gasoline,  when  used  for  generating  purposes.  The 
generating  material  having  been  ignited  and  burned  out,  the 
generator  is  hot  and  filled  with  vapor.  The  heated  generator 
vaporizes  a  portion  of  the  contained  gasoline  and  forms  sufficient 
pressure  to  force  the  remaining  gasoline  back  through  B  into  the 
supply  tank.  The  material  of  the  tube  B  permits  only  a  slow 
movement  of  the  gasoline  and  prevents  the  possibility  of  surging 
in  the  generator. 

The  initial  supply  of  vapor  being  generated,  the  needle-valve 
may  be  opened  and  the  gas  lighted  above  the  burner  7-7,  where 
it  should  burn  in  little  jets  at  each  opening  with  the  characteristic 
Bunsen  flame.  It  sometimes  happens  that  the  generator  is  not 
heated  sufficiently,  by  the  generating  flame,  to  vaporize  the 
necessary  gasoline  for  starting  the  burner;  in  this  case  liquid 
gasoline  will  be  forced  from  the  opening  G,  and  the  burner  will 
flare  up  intermittently  in  a  red  smoky  flame.  When  this  occurs 
the  burners  must  be  regenerated. 

Gasoline  Sad  Irons. — The  use  of  gaseous  or  liquid  fuel  is  always 
attended  by  an  element  of  danger,  because  of  the  possibility  of 
accidental  explosion.  The  use  of  gasoline,  the  most  highly 
volatile  of  all  liquid  fuels,  has,  however,  come  to  be  very 
generally  used  as  a  source  of  heat  for  domestic  purposes.  The 

19 


290 


MECHANICS  OF  THE  HOUSEHOLD 


danger  of  accident  in  the  use  of  gasoline  as  a  fuel  for  heating 
sad  irons  is  largely  due  to  ignorance  of  the  involved  mechanism 
or  carelessness  in  manipulation.  A  knowledge  of  the  principle 
included  in  their  operation,  together  with  an  observance  of  the 
possible  cause  of  accident,  will  reduce  the  element  of  danger  to 
a  negligible  quantity. 

The  use  of  gasoline  sad  irons  has  come  into  favor  because  of 
their  convenience  and  economy  in  operation.  These  irons,  in 
common  with  the  use  of  gasoline  in  its  other  applications  of 
heating  and  lighting,  are  made  in  a  great  many  forms  but  the 
principle  of  operation  is  confined  to  two  types. 


FIG.  203. — Gasoline  flat-iron  oper- 
ated by  a  heated  fuel  tank. 


FIG.  204. — Gasoline  flat-iron  show- 
ing the  position  of  the  cover  while 
initial  charge  of  gas  is  being  generated. 


First,  those  in  which  the  gasoline  is  forced  into  the  generator 
by  the  vapor  pressure,  from  the  heated  supply  tank;  and  second 
those  in  which  the  pressure  is  caused  by  pumping  air  into  the 
supply  tank  after  the  manner  of  the  hollow-wire  system  of 
lighting. 

The  first  type  of  iron  is  illustrated  in  Fig.  203.  The  same  iron 
is  shown  in  Fig.  204,  with  the  top  in  position  for  generating  vapor 
pressure  necessary  to  start  the  burner.  The  body  of  the  iron  A 
is  a  hollow  casting,  designed  to  receive  the  generator  and  burner 
in  such  position  that  the  bottom  portion  of  the  iron  may  be 
uniformly  heated.  The  generator  and  burner  are  shown  in 
detail  in  Fig.  205,  in  which  a  sectional  view  is  given  of  the  parts, 
cut  across  lengthwise  of  the  iron. 

In  starting  the  burner  for  use,  the  tank  is  first  filled — not  quite 
full — of  strained  gasoline.  The  precaution  of  straining  the  gaso- 


GASEOUS  AND  LIQUID  FUELS  291 

line  should  be  taken,  to  prevent  putting  into  the  tank  anything 
that  will  possibly  choke  the  needle-valve.  Alcohol  is  used  for 
generating  the  vapor  supply,  because  the  flame  does  not  black 
the  iron  and  fill  the  room  with  smoke  as  in  the  case  when  gasoline 
is  used  for  the  purpose.  When  the  alcohol  is  ignited,  the  cover- 
is  placed  in  position  as  shown  in  Fig.  204,  so  that  the  flame  may 
heat  not  only  the  generator  but  also  the  tank.  The  object  of 
heating  the  tank  is  that  the  heated  gasoline  may  furnish  pressure 
with  which  to  force  the  gasoline  into  the  generator.  When  the 
alcohol  used  for  generating  is  almost  burned  out,  the  valve  F  is 
slightly  opened  and  the  burner  lighted. 

As  shown  in  Fig.  205,  the  generator  G  is  a  brass  tube,  inclosing 
the  valve-stem  G,  which  terminates  in  the  needle-valve  V.     This 


FIG.   205. — Sectional  view  of  gasoline  flat-iron  generator  and  burner. 

valve  regulates  the  supply  of  gas  admitted  to  the  burner  and  is 
operated  by  the  hand-wheel  F.  When  the  gasoline  in  the  tank 
has  been  heated  the  necessary  amount,  the  vapor  in  G  is  allowed 
to  escape  through  the  valve  V.  The  vapor  is  discharged  into 
the  Bunsen  tube,  and  with  it  the  air  is  carried  in  through  the 
openings  E,  from  both  sides  of  the  iron.  The  burner  is  a  brass 
tube,  slotted  as  shown  at  H,  through  which  the  gas  escapes, 
forming  a  short  flame  of  large  area  close  to  the  part  of  the  iron 
to  be  heated.  The  size  of  the  flame  is  regulated  by  the  hand- 
wheel  F. 

The  tank  is  entirely  closed,  thr  plug  P  being  provided  with  a 
le  ad  washer  to  insure  a  tight  joint.  The  plug  is  further  provided 
with  a  soft  metal  center  which  acts  as  a  " safety-plug"  in  case  of 


292 


MECHANICS  OF  THE  HOUSEHOLD 


overheating.  Should  the  iron  at  any  time  become  too  hot,  the 
soft  metal  center  will  melt  and  the  released  pressure  in  the  tank 
will  put  out  the  burner  flame.  The  soft  metal  center  may  be 
renewed  with  a  drop  of  solder.  In  case  the  safety-plug  at  any 
time  is  melted,  the  hot  gasoline  will  spurt  from  the  opening  and 
immediately  vaporize.  This  of  course  would,  in  a  short  time, 
produce  an  explosive  atmosphere  which  if  ignited  would  be 
dangerous.  In  case  of  accident  the  iron  should  be  carried  to  the 
open  air  and  the  flame  smothered  with  a  cloth. 

Alcohol  Sad  Irons. — Irons  of  the  same  style  are  also  made  in 
which  alcohol  is  used  as  a  fuel.  The  alcohol  irons  differ  in  con- 
struction from  those  using  gasoline  only  in  the  amount  of  air 

that  is  mixed  with  the  vapor.  In 
general  appearance  the  two  styles 
look  very  much  alike,  but  in  the 
alcohol  iron  one  of  the  intakes  E 
is  entirely  closed  and  the  other 
opening  is  partially  closed. 

The  operation  of  these  irons  is 
identical  to  those  using  gasoline, 
but  they  are  preferred  by  those  who 

^^milii,  __^||    fear  the  use  of  that  fuel.     In  reality 

j  D       F  /         there    is    little    difference    in   the 

^  danger  attending  the  use  of  the 
two  liquids.  It  is  only  fair  to  say, 
however,  that  the  use  of  any  highly 
volatile  fuel  is  attended  with  some  danger  when  used  carelessly, 
but  with  a  reasonable  amount  of  care  and  a  knowledge  of  the 
mechanism  of  the  machine  in  use  the  danger  is  of  minor 
consequence. 

In  Fig.  206  is  illustrated  another  style  of  gasoline  sad  iron,  the 
working  principle  of  which  is  the  same  as  those  already  described 
but  the  supply  tank  is  not  heated  to  give  pressure  to  the  gasoline 
in  the  tank.  In  this  iron  the  tank  is  located  at  one  side  of  the 
iron  and  pressure  is  applied  with  an  air  pump  as  in  the  hollow- 
wire  system  of  lighting.  The  burner  is  generated  after  the 
manner  of  the  others  and  operated  in  exactly  the  same  manner. 
The  chief  difference  is  that  the  possibility  of  excessive  pressure 
through  overheating  is  eliminated. 


FIG.  206. — Gasoline  flat-iron  oper- 
ated by  an  air-pressure  fuel  tank. 


GASEOUS  AND  LIQUID  FUELS 


293 


Alcohol  Table  Stoves.— In  the  United  States  the  use  of  alcohol 
as  a  fuel  has  never  been  extensively  employed  because  of  the 
duty  imposed  on  its  manufacture  by  the  Federal  Government. 
In  1896  this  duty  was  removed  from  denatured  alcohol  and  the 
cost  was  sufficiently  reduced 
to  permit  a  great  extension 
in  its  use  as  a  fuel. 

Denatured  alcohol  is  any 
alcohol  to  which  has  been 
added  any  of  the  list  of  pre- 
scribed volatile  fluids  that  will 
render  the  alcohol  unfit  for 
use  in  beverages  and  not  ma- 
terially change  its  heating 
value.  Denatured  alcohol  is 
sold  at  a  price  that  will  per- 
mit its  use  in  small  flat-irons, 
table  stoves  and  other  forms  of 

burners  where  small  amounts          FlG  207._Aicohoi  vapor  stove. 
of  heat  are  generated  for  con- 
venience.    At  the  price  of  denatured  alcohol  as  generally  sold, 
it  cannot  compete  with  gasoline  and  kerosene  as  a  fuel. 

In  Fig.  207  is  shown  a  convenient  and  inexpensive  form  of 
table  stove,  in  which  the  vapor  of  alcohol  is  burned  in  practically 
the  same  manner  as  the  vapor  of  gasoline  in  the  burners  already 
described.  The  supply  of  alcohol  is  stored  in  a  tank  A,  and  fed 


FIG.  208. — Sectional  view  of  the  generator  and  burner  of  the  alcohol  vapor  stove. 

by  gravity  to  the  burner  B,  the  flame  from  which  resembles  that 
of  the  ordinary  gasoline  burner. 

The  generator  G  with  the  other  essential  parts  are  shown  in 
detail  in  Fig.  208.  The  reference  letters  indicate  the  same  parts 
in  the  detail  drawing  as  in  Fig.  207. 

The  alcohol  flows  from  the  supply  tank  through  the  pipe  C  to 
the  generator  G,  which  is  a  brass  tube  filled  with  copper  wires. 


294  MECHANICS  OF  THE  HOUSEHOLD 

The  vapor  for  starting  the  burner  is  generated  by  opening  the 
valve  V  and  allowing  a  small  amount  of  alcohol  to  flow  through 
the  orifice  C  into  the  pan  P  directly  below  the  generator.  The 
valve  is  then  closed  and  the  alcohol  ignited.  When  the  generat- 
ing flame  has  burned  out,  the  valve  V  is  again  opened  and  the 
vapor  which  has  generated  in  the  tube  escapes  at  the  orifice  C 
and  enters  the  Bunsen  tube  T,  (Fig.  207)  carrying  with  it  the 
proper  amount  of  air  to  produce  the  Bunsen  flame  at  each  of  the 
holes  of  the  burner. 

As  in  the  case  of  the  gasoline  burners  the  orifice  C  sometimes 
becomes  clogged  and  it  is  necessary  to  insert  a  small  wire  to  clear 
the  opening.  With  the  stove  is  provided  a  tool  for  this  purpose. 
With  stoves  of  this  kind,  the  supply  tank  must  not  be  tightly 
closed,  because  any  pressure  in  the  tank  would  cause  it  to  become 
dangerous.  The  alcohol  is  fed  to  the  generator  entirely  by 
gravity.  The  stopper  of  the  tank  contains  a  small  hole  at  the 
top  which  should  be  kept  open  to  avoid  the  generation  of  pressure 
should  the  tank  become  accidentally  heated. 

,  Stoves  of  this  kind  may  be  conveniently  used  for  a  great  variety 
of  household  purposes,  and  when  intelligently  handled  are  rela- 
tively free  from  danger. 

Danger  from  Gaseous  and  Liquid  Fuels. — All  combustible 
gases  or  vapors,  when  mixed  within  definite  amounts,  are  explo- 
sive. The  violence  of  the  explosion  will  be  in  proportion  to  the 
volumes  of  the  gas  and  the  condition  of  confinement. 

When  gasoline  or  other  volatile  fuel  is  vaporized  in  a  closed 
room,  there  is  danger  of  an  explosion,  should  the  mixture  of  the 
vapor  and  air  reach  explosive  proportions.  It  is  dangerous  to 
enter  a  room  with  a  lighted  match  or  open-flame  lamp,  where 
gaseous  odor  is  markedly  noticeable.  In  case  of  danger  of  this 
kind  the  windows  and  doors  should  be  immediately  opened  to 
produce  the  most  rapid  ventilation. 

In  the  act  of  igniting  the  flame  in  a  gas  or  vapor  stove,  the 
lighter  should  be  made  ready  before  the  gas  is  turned  on.  Ex- 
plosions in  gas  and  vapor  stoves  are  usually  due  to  carelessness 
in  igniting  the  fuel.  It  should  be  kept  constantly  in  mind  that, 
if  a  combustible  gas  is  allowed  to  escape  and  mix  with  air  in 
any  space  and  then  ignited,  an  explosion  of  more  or  less  violence 
is  sure  to  occur. 


GASEOUS  AND  LIQUID  FUELS  295 

Gasoline  and  kerosene  are  lighter  than  water  and  will  float  on 
its  surface.  The  flames  from  these  oils  are  aggravated  when 
water  is  used  in  attempting  to  extinguish  them.  The  burning 
oil  floating  on  the  surface  of  the  water  increases  the  burning 
surface. 

Burning  oil  must  be  either  removed  to  a  place  where  danger 
will  not  result  or  the  flames  must  be  smothered.  In  case  of  a 
small  blaze,  the  fire  may  be  extinguished  with  a  cloth,  preferably 
of  wool,  or  if  circumstances  will  permit,  with  ashes  sand  or  earth. 

Alcohol  dissolves  in  water  and  ma,y,  therefore,  be  diluted  to  a 
point  where  it  will  no  longer  burn. 

ACETYLENE-GAS  MACHINES 

Acetylene  is  a  gas  that  is  generated  when  water  is  absorbed 
by  calcium  carbide,  after  the  manner  in  which  carbonic  acid  gas 
is  evolved  when  lime  slakes  with  water,  but  with  the  liberation 
of  a  larger  amount  of  the  combustible  gas. 

Calcium  carbide  is  a  product  resulting  from  the  union  of  lime 
and  coke,  fused  in  an  electric  furnace  to  form  a  grayish-brown 
mass.  It  is  brittle  and  more  or  less  crystalline  in  structure  and 
looks  much  like  stone.  It  will  not  burn  except  when  heated  with 
oxygen.  A  cubic  foot  of  the  crushed  calcium  carbide  weighs 
160  pounds. 

Calcium  carbide — or  carbide  as  it  is  ordinarily  termed — may 
be  preserved  for  any  length  of  time  if  kept  sealed  from  the  air, 
but  the  ordinary  moisture  of  the  atmosphere  gradually  slakes  it 
and  after  exposure  for  a  considerable  time  it  changes  into  slaked 
lime.  The  carbide  itself  has  no  odor,  but  in  the  air  it  is  always 
attended  by  the  penetrating  odor  of  acetylene,  because  of  the  gas 
liberated  by  the  moisture  absorbed  from  the  air. 

If  protected  from  moisture,  calcium  carbide  cannot  take  fire, 
being  like  lime  in  this  respect;  it  is  therefore  a  safe  substance  to 
store.  It  is  transported  under  the  same  classification  as  hard- 
ware, and  will  keep  indefinitely  if  properly  sealed. 

A  pound  of  pure  carbide  yields  5^  cubic  feet  of  acetylene,  but 
in  commercial  form,  as  rated  by  the  National  Board  of  Fire 
lTM<l(M-\vritcrs,  lump  carbide  is  estimated  at  ^  cubic  feet  per 
pound.  In  the  generation  of  acetylene,  exact  weights  of  carbide 


296  MECHANICS  OF  THE  HOUSEHOLD 

and  water  always  enter  into  combination,  i.e.,  64  parts  of  carbide 
to  34  parts  of  water,  and  a  definite  amount  of  heat  is  evolved  for 
each  part  of  carbide  consumed. 

Uncontrolled,  the  gas  burns  with  a  bright  but  not  brilliant 
flame  and  with  a  great  deal  of  smoke,  but  when  used  in  a  burner 
suited  for  its  combustion  it  burns  with  a  clear  brilliant  flame  of  a 
quality  approaching  sunlight.  While  carbide  is  not  explosive 
nor  inflammable,  it  may,  if  it  finds  access  to  water,  create  a 
pressure  such  as  to  burst  its  container,  and  it  is  not  impossible 
that  heat  might  be  generated  sufficient  to  ignite  the  gas  under 
such  conditions.  That  such  condition  would  often  occur  is  not 
at  all  probable.  When  water  is  sprinkled  upon  carbide,  in 
quantity  such  that  it  will  all  be  taken  up,  the  resultant  slaked 
lime  is  left  dry  and  dusty,  and  occupies  more  space  than  the 
original  carbide.  When  more  than  enough  water  is  employed, 
the  remaining  mixture  of  lime  and  water  is  whitewash. 

Chemically  considered,  acetylene  is  C2H2;  it  is  composed  of 
carbon  and  hydrogen  and  belongs  to  a  class  of  compounds  known 
as  hydrocarbons,  represented  in  nature  by  petroleum,  natural 
gas,  etc.  It  is  composed  of  92.3  per  cent,  carbon  and  7.7  per 
cent,  of  hydrogen,  both  combustible  gases.  It  is  a  non-poison- 
ous, colorless  gas,  with  a  persistent  and  penetrating  odor.  Its 
presence  in  the  air,  to  the  extent  of  1  part  in  1000  is  distinctly 
perceptible.  When  burning  brightly  in  a  jet,  there  is  no  per- 
ceptible odor.  When  completely  burned  it  requires  for  its  com- 
bustion 2J£  times  its  volume  of  oxygen. 

All  combustible  gases,  when  mixed  with  air  and  ignited,  pro- 
duce more  or  less  violent  explosions.  Acetylene  is  no  exception 
to  the  rule,  and  when  allowed  to  escape  into  any  enclosed  space 
it  will  quickly  produce  a  violently  explosive  mixture,  so  that  it  is 
always  dangerous  to  enter  a  room  or  basement  with  a  lamp  or 
flame  of  any  kind  where  the  odor  of  gas  is  perceptible.  This  is 
quite  true  with  a  combustible  gas  of  any  kind,  but  with  acetylene 
all  mixtures  from  3  to  30  per  cent,  are  capable  of  being  exploded 
with  greater  or  less  violence. 

The  kindling  point  of  acetylene  is  lower  than  coal  gas  or 
gasoline  gas.  To  ignite  either  of  the  latter  gases,  a  flame  is 
necessary  to  start  the  combustion,  but  a  spark  or  a  glowing  cigar 
is  sufficient  to  ignite  acetylene.  It  should  therefore  be  borne  in 


GASEOUS  AND  LIQUID  FUELS  297 

mind  that  acetylene  is  not  only  explosive  when  mixed  with  air 
but  that  it  is  very  easy  to  ignite.  Under  ordinary  pressures 
pure  acetylene  is  not  explosive,  but  at  pressure  above  15  pounds 
to  the  square  inch  explosions  sometimes  occur  where  proper  pre- 
cautions are  not  observed.  At  all  pressures  such  as  are  required 
for  household  purposes  acetylene  is  as  safe  for  use  as  any  other 
gas. 

Although  acetylene  is  in  danger  of  exploding  when  under- 
pressure, it  is  perfectly  safe,  when  the  proper  conditions  are 
observed,  in  tanks  for  a  great  many  kinds  of  portable  lights. 

Where  acetylene  is  used  in  portable  tanks  under  pressure, 
advantage  is  taken  of  its  solubility  in  acetone.  This  is  a  product 
of  the  distillation  of  wood  which  possesses  the  property  of  ab- 
sorbing acetylene  to  a  remarkable  degree.  In  addition  to  this 
property  is  the  more  important  one  of  rendering  the  acetylene 
non-explosive  when  under  pressure.  The  tanks  for  its  storage 
are  filled  with  asbestos  or  other  absorbent  material  that  is 
saturated  with  acetone.  The  acetylene  is  then  forced  into  the 
tanks  under  pressure  and  is  absorbed  by  the  acetone.  The 
safety  of  this  means  of  storage  lies  in  the  degree  of  perfection  to 
which  the  tanks  are  filled  with  the  absorbent  material.  There 
must  be  no  space  anywhere  in  the  tank  where  undissolved 
acetylene  can  exist.  Its  freedom  from  danger  under  such 
conditions  has  been  thoroughly  demonstrated  in  its  use  for 
railroad  and  automobile  lamps. 

The  use  of  acetylene  as  a  fuel  for  cooking  and  for  the  various 
other  purposes  of  domestic  use  is  successfully  accomplished  in 
burners  that  give  the  blue  flame  desired  for  such  purposes. 
Complete  cooking  ranges  and  various  other  heating  and  cooking 
devices  are  regularly  sold  by  dealers  in  heating  appliances,  while 
water-heaters,  hot-plates,  chafing-dish  heaters,  etc.,  are  as  much 
a  possibility  as  with  any  other  of  gaseous  fuel  and  in  as 
reasonably  an  inexpensive  way. 

Coal  gas,  containing  as  it  does  sufficient  carbon  monoxide  to 
render  it  poisonous,  will  cause  death  when  inhaled  for  any  length 
of  time,  but  acetylene  under  the  same  conditions  will  have  no 
deleterious  effect. 

Types  of  Acetylene  Generators.— There  are  two  general 
methods  of  generating  acetylene  for  domestic  illuminating  and 


298 


MECHANICS  OF  THE  HOUSEHOLD 


heating  purposes:  that  of  adding  carbide  to  water,  and  that  in 
which  the  water  is  mixed  with  carbide.  The  two  types  are 
illustrated  in  the  diagrams  shown  in  Figs.  209  and  210.  The 
first  method,  that  in  which  the  carbide  is  dropped  into  water,  is 
shown  in  Fig.  209.  The  tank  A  is  the  generator  and  B  is  the 
receiver  or  gas-holder.  The  tank  A  holds  a  considerable  quantity 
of  water  and  is  provided  with  a  container  C  for  holding  the  supply 
of  carbide.  The  tank  A  is  connected  with  the  gas-holders  by  a 
pipe  which  extends  above  the  water  line  in  the  tank  B,  where 
the  gas  is  allowed  to  collect  in  the  gas-holder  G.  A  charge  of 
carbide,  sufficient  to  fill  the  holder  with  gas,  is  pushed  into  the 
tank  A  by  raising  the  lever  H.  Immediately  the  water  begins 
to  combine  with  the  carbide  and  the  bubbles  of  gas  pass  up 


t 

t»        \ 
G 

'* 

;  Er~E- 

•^IF^fj^IlIz- 

=^:: 

:~ 

3£^I: 

;>:— 

•E- 

r~-3-3 

~- 

^ 

r 

HI 

A 

FIG.  209. — Diagram  of  a  carbide-to- 
water  acetylene-gas  generator. 


A  B 

FIG.  210. — Diagram  of  a  water-to- 
carbide  acetylene-gas  machine. 


through  the  water  and  are  conducted  into  the  tank  B.  The 
holder  G  is  lifted  by  the  gas  and  its  weight  furnishes  the  pressure 
necessary  to  force  the  gas  into  the  pipes,  which  conduct  it  to  the 
burners.  If  this  machine  were  provided  with  the  proper  mechan- 
ism to  feed  into  the  generator  a  supply  of  carbide  whenever  the 
gas  in  the  holder  is  exhausted,  the  machine  would  represent  the 
modern  "carbide  to  water"  generator. 

The  "water to  carbide"  generator  isshowndiagrammaticallyin 
Fig.  210.  As  in  the  other  figure,  A  is  the  generator  and  B  is  the 
gas-holder.  A  supply  of  carbide  S  is  placed  in  the  generator 
and  water  from  a  tank  C  is  allowed  to  drip  or  spray  onto  the 
carbide.  The  gas  collects  in  the  gas-holder  as  before.  This 
apparatus  represents  in  principle  the  parts  of  a  machine  for 
generating  acetylene  by  this  process.  The  actual  machines  are 


GASEOUS  AND  LIQUID  FUELS  299 

arranged  to  perform  the  functions  necessary  to  make  the  machines 
automatic  in  their  action. 

Whatever  the  type  of  the  machine,  the  object  is  to  keep  in  the 
holders  a  sufficient  amount  of  gas  with  which  to  supply  the 
demand  made  on  the  plant.  Machines  representing  each  of  the 
types  described  are  to  be  obtained,  but  the  greater  number  of  those 
manufactured  are  of  the  "carbide  to  water"  form. 

In  the  formative  period  of  acetylene  generators  many  accidents 
of  serious  consequence  resulted  from  imperfect  mechanism. 
Imperfections  have  been  gradually  eliminated  until  the  machines 
which  have  survived  are  efficient  in  action  and  mechanically 
free  from  dangerous  eccentricities. 

The  qualities  demanded  of  a  good  g'enerator  are :  There  must 
be  no  possibility  of  an  explosive  mixture  in  any  of  the  parts;  it 
must  insure  a  cool  generation  of  gas;  it  must  be  well-constructed 
and  simple  to  operate;  it  should  create  no  pressure  above  a  few 
ounces;  it  should  be  provided  with  an  indicator  to  show  how  low 
the  charge  of  carbide  has  become  in  order  that  it  may  be  re- 
charged in  due  season,  and  it  must  use  up  the  carbide  completely. 

Because  of  the  fact  that  the  greater  number  of  acetylene-gas 
machines  of  today  are  of  the  " carbide  to  water"  type,  in  the 
description  to  follow  that  type  of  machine  is  used.  They  are 
generally  made  in  two  parts,  one  part  containing  the  generating 
apparatus  and  the  other  acting  as  gasometer  (gas-holder), 
but  some  machines  are  made  in  which  one  cell  contains  both  the 
generator  and  gasometer. 

In  Fig.  211  is  shown  a  two-part,  gravity-fed  machine,  in  which 
all  of  the  internal  working  parts  are  exposed  to  view.  The 
tank  (a),  as  in  the  diagram,  is  the  generator  and  the  tank  (6) 
contains  the  gasometer  marked  G.  Each  tank  possesses  a 
number  of  appliances  which  are  necessary  to  make  the  machine 
automatic  in  its  action.  The  part  C  of  the  generator  contains 
the  supply  of  carbide,  broken  into  small  pieces,  a  portion  of 
which  is  dropped  into  the  water  whenever  additional  gas  is 
required.  The  feed  mechanism  F  is  controlled  by  the  gasometer 
bell  G,  which  is  buoyed  up  by  the  gas  it  contains.  When  the 
supply  of  gas  becomes  low,  the  descending  bell  carries  with  it 
the  end  of  the  lever  F,  which  is  attached  to  the  feed  valve; 
this  motion  raises  the  feed  valve  and  allows  some  of  the  carbide 


300 


MECHANICS  OF  THE  HOUSEHOLD 


to  fall  into  the  water.  The  gas  that  is  immediately  generated 
passes  into  the  gasometer  through  the  pipe  P,  and  as  the  bell  is 
raised  by  the  accumulating  gas  the  valve  V  is  closed. 

The  gas  as  it  enters  the  gasometer  passes  through  a  hollow 
device  W,  that  looks  like  an  inverted  T,  the  lower  edge  of  which  is 
tooth-shaped  and  extends  below  the  surface  of  the  water.  The 
gas,  in  passing  this  irregular  surface,  is  broken  up  and  comes 
through  the  water  in  little  bubbles,  in  order  that  it  may  be  washed 
clean  of  dust.  This  device  also  prevents  the  return  of  the  gas 
to  the  generator  tank  during  the  process  of  charging. 


(a) 
FIG.  211. — Sectional  view  of  the  Colt  acetylene- gas  machine. 

The  gas  escapes  from  the  bell  through  the  pipe  S  to  the  filter  D, 
where  any  dust  that  may  have  escaped  the  washing  process  is 
removed  by  a  felt  filter.  It  finally  leaves  the  machine  by  the 
pipe  L,  at  which  point  it  enters  the  system  through  which  it  is 
conveyed  to  the  different  lighting  fixtures. 

It  will  be  noticed  that  the  tank  (6)  is  divided  into  two  compart- 
ments, the  upper  portion  containing  the  water  in  which  the  gas- 
ometer floats.  The  lower  compartment  is  also  partly  filled 
with  water  which  acts  as  a  safety  valve  to  prevent  any  escape  of 


GASEOUS  AND  LIQUID  FUELS 


301 


gas  into  the  room  in  which  the  generator  is  located.  The  lower 
end  of  the  pipes  P  and  S  are  immersed  in  the  water  at  the  bottom 
chamber  of  the  tank,  from  which  the  gas  could  escape  in  case  too 
much  is  generated  and  finally  exit  through  the  vent  pipe  U  to 
the  outside  air. 

The  float  A  in  the  tank  (a)  is  a  safety  device  that  prevents  the 
introduction  of  carbide  unless  the  tank  contains  a  full  supply  of 
water.  The  float  is  a  hollow  metal  cylinder  connected  by  a  rod 
to  a  hinged  cup  under  the  bottom  opening  of  the  carbide  holder. 
When  the  water  is  withdrawn  from  the  generator,  the  float  falls 
and  the  cup  shuts  off  the  carbide  outlet. 


FIG.  212. — Sectional  view  of  a  house  equipped  with  acetylene  lights  and  domestic 

heating  apparatus. 

The  accumulation  of  lime,  from  the  disintegrated  carbide, 
requires  occasional  removal  from  the  tank  (a) ;  the  valve  K  is 
provided  for  this  purpose.  The  lever  S  is  used  to  stir  up  the  lime 
which  is  deposited  on  the  bottom  of  the  tank,  that  it  may  be 
carried  out  with  the  discharged  water. 

Machines  of  this  kind  that  are  safeguarded  against  leakage  of 
gas  or  the  possibility  of  accumulated  pressure  are  practically  free 
from  danger  in  the  use  of  acetylene.  The  accidental  leakage  of 
gas  from  defective  pipes  and  fixtures  produce  only  the  element  of 
risk  that  is  assumed  with  the  use  of  any  other  form  of  gas  for 
illuminating  purposes. 


302  MECHANICS  OF  THE  HOUSEHOLD 

Acetylene  is  distributed  through  the  house  in  pipes  in  the 
same  manner  as  for  ordinary  illuminating  gas.  The  sizes  of;the 
pipes  to  suit  the  varying  conditions  of  use  are  regulated  by  rules 
provided  by  the  National  Board  of  Fire  Underwriters.  These 
rules  state  definitely  the  sizes  of  pipes  required  for  machines  of 
different  capacities.  Rules  of  this  kind  and  others  that  specify 
all  matters  relating  to  the  use  of  acetylene  may  be  obtained 
from  any  fire  insurance  agent. 

The  general  plan  of  piping  is  shown  in  Fig.  212.  The  gen- 
erator G  is  in  this  case  a  " water  to  carbide"  machine  and  is 
shown  connected  to  the  kitchen  range,  as  well  as  the  pipe  system 
which  may  be  traced  to  the  lamps  in  the  different  rooms,  to  the 
porch  lights  and  to  the  boulevard  lamp  in  front  of  the  building. 


FIG.  213. — Acety-         FIG.    214. — Elec-         FIG.  215. — Electric  ig- 
lene  gas  burner.       trie  igniter  for  acety-     niter    for    acetylene   gas 
lene  gas  burners.  burners. 

The  type  of  burner  used  in  acetylene  lamps  is  shown  in  Fig. 
213.  The  gas  issues  from  two  openings  to  form  the  jet  as  it 
appears  in  the  engraving.  These  burners  are  made  in  sizes  to 
consume  Y±,  %,  %,and  1  foot  per  hour  depending  on  the  amount  of 
light  demanded. 

Gas  Lighters. — The  acetylene  gas  jets  are  lighted  ordinarily  with 
a  match  or  taper  but  electric  igniters  are  often  used  for  that  pur- 
pose. Electric  lighters  for  acetylene  lamps  are  practically  the 
same  as  those  used  with  ordinary  gas  lamps  but  they  must  be 
adapted  to  the  type  of  burner  on  which  they  are  used.  Electric 
igniters  that  are  intended  to  be  used  with  lamps  placed  in  inacces- 
sible places  are  different  in  construction  from  those  within  reach. 
In  Figs.  214  and  215  are  illustrated  two  forms  of  igniters  that 
are  intended  to  be  used  on  bracket  or  pendent  lamps.  They 


GASEOUS  AND  LIQUID  FUELS 


'    303 


differ  in  mechanical  construction  lo  suit  two  different  conditions. 
Fig.  214  is  an  igniter  in  which  is  also  included  the  gas-cock.  The 
gas  is  lighted  by  pulling  a  cord  or  chain  attached  to  the  lever  L. 
The  movement  of  this  lever  turns  on  the  gas  and  at  the  same 
time  brings  the  piece  C  in  contact  with  the  wire  A  to  complete 
an  electric  circuit.  As  the  contact  between  these  two  pieces  is 
broken,  a  spark  is  formed  that  ignites  the  gas  escaping  from  the 
burner  at  B.  On  releasing  the  lever  a  spring  returns  the  piece  C 
to  its  original  position.  The  light  is  extinguished  by  a  second 
pull  of  the  lever. 

Fig.  215  illustrates  a  style  of  igniter  which  may  be  attached 
to  an  ordinary  gas-cock.  It  is  attached  to  the  stem  of  the  burner 
by  a  clamp  D.  The  gas  is  turned 
on  by  the  usual  gas-cock  and  by  pull-  w 
ing  the  chain  at  the  left  the  jet  is 
lighted.  In  pulling  the  chain  the  arm 
A  is  raised  and  carries  with  it  the 
arm  B.  When  the  arms  A  and  B 
touch,  an  electric  circuit  is  formed 
with  a  battery  and  spark  coil.  When 
the  desired  position  of  the  arms  is 
reached,  the  points  separate  to  form 
an  electric  flash  which  lights  the  gas. 

Fig.  216  illustrates  in  A  the  method        FIG.  216.— Diagram  of  eiec- 
of  installing  electric  igniters  like  those     tric  igniters  attached  to  gas 

,        burners. 

described.     A  battery  B  and  a  spark 

coil  S  are  joined  in  circuit  as  shown.  The  gas  pipe  acts  as  one 
of  the  wires  of  the  circuit.  A  battery  of  four  dry  cells  is  com- 
monly used  for  the  purpose.  The  spark  coil  is  a  simple  coil  of 
wire  wound  on  a  heavy  iron  core,  which  serves  to  intensify  the 
spark  when  the  circuit  is  broken.  In  using  the  igniter,  it  is 
only  necessary  to  see  that  the  cells  are  joined  in  series  with  the 
coil  and  attached  to  the  insulated  part  of  the  igniter.  As  already 
explained  the  action  of  the  igniter  is  to  close  the  circuit  and  im- 
mediately break  the  contact  at  a  point  where  the  spark  will  ig- 
nite the  gas.  On  being  released  the  igniter  returns  to  its  original 
position. 

In  the  fixture  shown  at  C  is  an  igniter  such  as  is  used  in  places 
that  cannot  be  conveniently  reached.     To  light  the  jet,  the  circuit 


304  MECHANICS  OF  THE  HOUSEHOLD 

is  completed  by  turning  the  switch  at  W.  As  soon  as  the  gas  is 
lighted  the  switch  is  again  turned  to  break  the  igniter-circuit. 
In  this  device  the  current  passes  through  a  magnet  coil  in  the 
igniter  which  acts  to  open  and  close  the  circuit  with  the  same  effect 
as  in  the  others. 

Acetylene  Stoves. — Stoves  in  which  acetylene  is  used  as  a  fuel 
are  quite  similar  in  construction  to  those  which  burn  coal  gas. 
The  principle  of  operation  is  that  of  mixing  the  acetylene  with  air 
in  proper  proportion  so  as  to  produce  complete  combustion 
when  burned. 


CHAPTER  XIII 
ELECTRICITY 

The  adaptability  of  electricity  to  household  use  for  lighting; 
heating  and  the  generation  of  power  has  brought  into  use  a  host 
of  mechanical  devices  that  have  found  a  permanent  place  in 
every  community  where  electricity  may  be  obtained  at  a  reason- 
able rate,  or  where  it  can  be  generated  to  advantage  in  small 
plants. 

Because  of  its  cleanliness  and  convenience,  electricity  is  used 
in  preference  to  other  forms  of  lighting,  even  though  its  cost  is 
relatively  high.  Electric  power  for  household  purposes  is  con- 
stantly finding  new  applications  and  will  continue  to  increase  in 
favor  because  its  use  as  compared  with  hand  power  is  remark- 
ably inexpensive.  Small  motors  adapted  to  most  of  the  ordi- 
nary household  uses  are  made  in  convenient  sizes  and  sold  at 
prices  that  are  conducive  to  their  greater  use.  Human  energy 
is  far  too  precious  to  be  expended  in  household  drudgery 
where  mechanical  power  can  be  used  in  its  place  and  often  to 
greater  advantage. 

Electric  heating  devices  compete  favorably  with  many  of  the 
established  forms  of  household  heating  appliances,  the  electric 
flat-iron  being  a  notable  example.  In  all  applications  where 
small  amounts  of  heat  are  required  for  short  periods  of  time, 
electricity  is  used  at  a  cost  that  permits  its  use,  in  competition 
with  other  forms  of  heating. 

The  remarkable  advance  that  has  taken  place  in  elect  ic 
transmission  in  the  past  few  years  tends  to  an  enormous  increase 
in  its  use.  The  constant  increase  in  its  use  for  lighting,  heating 
and  power  purposes  is  due  in  a  great  measure  to  the  development 
of  efficient  electric  generating  plants  from  which  this  energy  may 
be  obtained  at  the  least  cost.  In  those  communities  where 
20  305 


306  MECHANICS  OF  THE  HOUSEHOLD   ' 

hydro-electric  generation  is  possible  its  field  of  application  is 
almost  without  end. 

Incandescent  Electric  Lamps. — Anything  made  in  the  form  of 
an  illuminating  device,  in  which  the  lighting  element  is  rendered 
incandescent  by  electricity,  may  properly  be  called  an  in- 
candescent lamp,  whether  the  medium  is  incandescent  gas  as  in 
the  Moore  lamp,  an  incandescent  vapor  as  the  Cooper  Hewitt 
mercury-vapor  lamp,  or  the  incandescent  filament  of  carbon  or 
metal  such  as  is  universally  used  for  lighting. 

From  the  year  1879,  when  Mr.  Edison  announced  the  perfec- 
tion of  the  incandescent  electric  lamp,  until  1903,  when  for  a  short 
period  tantalum  lamps  were  used,  very  little  improvement  had 
been  made  in  the  carbon-filament  lamp.  Immediately  following 
the  introduction  of  the  tantalum  lamp  came  the  tungsten  lamp, 
which  because  of  its  wonderfully  increased  capability  for  pro- 
ducing light  has  extended  artificial  illumination  to  a  degree 
almost  beyond  comprehension.  The  influence  of  the  tungsten 
lamp  has  induced  a  new  era  of  illumination  that  has  affected  the 
entire  civilized  world.  The  development  of  the  high-efficiency 
incandescent  lamp  has  brought  about  a  revolution  in  electric 
lighting.  Its  use  is  universal  and  its  application  is  made  in  every 
form  of  electric  illumination. 

Regardless  of  the  immense  number  of  tungsten  lamps  in  use, 
the  carbon-filament  lamp  is  still  employed  in  great  numbers  and 
will  probably  continue  in  use  for  a  long  time  to  come.  In 
places  where  lamps  are  required  for  occasional  use  and  for  short 
intervals  of  time,  the  carbon  filament  still  finds  efficient  use. 
In  one  form  of  manufacture  the  carbon  filament  is  subjected  to  a 
metalizing  process  that  materially  increases  its  efficiency. 
This  form,  known  commercially  as  the  GEM  lamp,  fills  an 
important  place  in  electric  lighting. 

Of  the  rare-metal  filament  lamps,  those  using  tungsten  and 
tantalum  are  in  general  use,  but  the  tungsten  lamps  give  results 
so  much  superior  in  point  of  economy  in  current  consumed 
that  the  future  filament  lamps  will  beyond  doubt  be  of  that 
type  unless  some  other  material  is  found  that  will  give  better 
results. 

The  filaments  of  the  first  tungsten  lamps  were  very  fragile 
and  were  so  easily  broken  that  their  use  was  limited,  but  in  a 


ELECTRICITY  307 

very  short  time  methods  were  found  for  producing  filaments 
capable  of  withstanding  general  usage  and  having  an  average 
life  of  1000  hours  of  service.  These  lamps  give  an  efficiency  of 
1.1  to  1.25  watts  per  candlepower  of  light,  as  will  be  later  more 
fully  explained.  This,  as  compared  with  the  carbon-filament 
lamps  which  average  3.1  to  4.5  watts  per  candlepower,  gives  a 
remarkable  advantage  to  the  former.  The  tungsten  lamp  has  a 
useful  life  that  for  cost  of  light  is  practically  one-third  that  of  the 
carbon-filament  lamp. 

The  metal  tungsten,  from  which  the  lamp  filament  is  made, 
was  discovered  in  1871.  It  is  not  found  in  the  metallic  state 
but  occurs  as  tungstate  of  iron  and  manganese  and  as  calcium 
tungstate.  Up  to  1906  it  was  known  only  in  laboratories  and 
on  account  of  its  rarity  the  price  was  very  high.  As  greater 
bodies  of  ore  were  found  and  the  process  of  extraction  became 
better  known,  the  price  soon  dropped  to  a  point  permitting  its 
use  for  lamp  filaments  in  a  commercial  scale. 

Pure  tungsten  is  hard  enough  to  scratch  glass.  Its  fusing 
point  is  higher  than  any  other  known  metal ;  under  ordinary  con- 
ditions it  is  almost  impossible  to  melt  it  and  this  property  gives 
its  value  as  an  incandescent  filament.  One  of  the  laws  that  affect 
the  lighting  properties  of  incandescent  lamps  is:  "the  higher  the 
temperature  of  the  glowing  filament,  the  greater  will  be  the 
amount  of  light  furnished  for  a  given  amount  of  current  con- 
sumed." The  high  melting  point  permits  the  tungsten  filament 
to  be  used  at  a  higher  temperature  than  any  other  known  mate- 
rial. Tungsten  is  not  ductile,  and  in  ordinary  form  cannot  be 
drawn  into  wire.  Because  of  this  fact,  the  filaments  of  the 
first  lamps  were  made  by  the  "paste"  process,  which  consisted 
of  mixing  the  powdered  metal  with  a  binding  material,  in  the 
form  of  gums,  until  the  mass  acquired  a  consistency  in  which  it 
might  be  squirted  through  a  minute  orifice  in  a  diamond  dye.  The 
resulting  thread  was  dried,  after  which  it  was  heated,  and  finally 
placed  in  an  atmosphere  of  gases  which  attacked  the  binding  ma- 
terial without  affecting  the  metal.  When  heated  by  electric- 
ity in  this  condition,  the  particles  of  metal  fused  together  to  form 
a  filament  of  tungsten.  While  the  "paste"  filaments  were  never- 
satisfactory  in  general  use,  their  efficiency  as  a  light-producing 


308 


MECHANICS  OF  THE  HOUSEHOLD 


Glass  Bulb 


Top  Anchors 


agent  inspired  a  greater  diligence  in  the  search  for  a  more  durable 
form. 

Although  tungsten  in  ordinary  condition  is  not  at  all  ductile, 
methods  were  soon  found  for  making  tungsten  wire  and  the 
wire-filament  lamps  are  now  those  of  general  use.  One  process 
of  producing  the  drawn  wire  is  that  of  filling  a  molten  mass  of  a 
ductile  metal  with  powdered  tungsten  after  which  wire  is  drawn 
from  the  mixture  in  the  usual  way.  The  enclosing  metal  is  then 
removed  by  chemical  means  or  volatilized  by  heat. 

Of  the  difficulties  encountered  in  the  use  of  metal-filament 
lamps  that  of  the  low  resistance  offered  by  the  wire  was  over- 
come by  using  filaments  very 
small  in  cross-section  and  of  as 
great  length  as  could  be  con- 
veniently handled.  The  long 
tungsten  filament  requires  a 
method  of  support  very  differ- 
ent from  the  carbon  lamp. 
The  characteristic  form  of 
tungsten  lamps  is  shown  in 
Fig.  217,  in  which  the  various 
parts  of  the  lamp  are  named. 

The  filament  of  an  incandes- 
cent lamp  is  heated  because  of 
the  current  which  passes 
through  it.  The  electric  pres- 
sure furnished  by  the  voltage,  forces  current  through  the  filament 
in  as  great  an  amount  as  the  resistance  will  permit.  A  16-candle- 
power  carbon  lamp  attached  to  a  110-volt  circuit  requires  practi- 
cally 1/2  ampere  of  current  to  render  the  filament  incandescent;  the 
filament  resistance  must,  therefore,  allow  the  passage  of  Y^  ampere. 
With  a  given  size  of  filament,  its  length  must  be  such  as  will 
produce  the  desired  resistance.  A  greater  length  of  this  filament 
would  give  more  resistance  and  a  correspondingly  less  amount 
of  current  would  give  a  dim  light  because  of  its  lower  temperature. 
Likewise,  a  shorter  filament  would  allow  more  current  to  pass 
and  a  brighter  light  would  result.  When  the  size  and  length  of 
filament  is  once  found  that  will  permit  the  right  amount  of  current 
to  pass,  if  the  voltage  is  kept  constant,  the  filaments  will  always 


Brass  Screw^ 
Shell  of  Base 


Glass  Insulation 


FIG. 


Brass  Cap  Contact 

217. — An  Edison  Mazda  lamp 
and  its  parts. 


ELECTRICITY  309 

burn  with  the  same  brightness.  This  is  in  accordance  with  Ohm's 
law  which  as  stated  in  a  formula  is 

E  =  RC 

that  is  E,  the  electromotive  force  in  volts,  is  always  equal  to  the 
product  of  the  resistance  R,  in  ohms,  and  the  current  C,  in 
amperes. 

In  the  incandescent  lamp,  if  the  electrotromotive  force  is  110 
volts  and  the  current  is  Y%  ampere,  the  resistance  will  be  220  ohms 
and  as  expressed  by  the  law 

110  =  220  X  0.5 

From  this  it  is  seen  that  any  change  in  the  voltage  will  produce 
a  corresponding  change  in  the  current  to  keep  an  equality  in  the 
equation.  If  the  voltage  increases,  the  current  also  increases 
and  the  lamp  burns  orighter.  Should  the  voltage  decrease  the 
current  will  decrease  and  the  lamp  will  burn  dim.  This  dim- 
ming effect  is  noticeable  in  any  lighting  system  whenever  there 
occurs  a  change  in  voltage. 

The  quantity  of  electricity  used  up  in  such  a  lamp  is  expressed 
in  watts,  which  is  the  product  of  the  volts  and  amperes  of  the 
circuit.  In  the  lamp  described,  the  product  of  the  voltage  (110) 
by  the  amount  of  passing  current  (%  ampere)  is  55  watts.  With 
the  above  conditions  the  16  candlepower  of  light  will  require  3.43 
watts  in  the  production  of  each  candlepower.  The  best  per- 
formance of  carbon-filament  lamps  give  a  candlepower  for  each 
3.1  watts  of  energy. 

The  filament  of  the  tungsten  lamp  must  offer  a  resistance 
sufficient  to  prevent  only  enough  current  to  pass  as  will  raise 
its  temperature  to  a  point  giving  the  greatest  permissible  amount 
of  light,  and  yet  not  destroy  the  wire.  The  high  fusing  point 
and  the  low  specific  heat  of  tungsten  permits  the  filament  to  be 
heated  to  a  higher  temperature  than  the  carbon  filament  and  with 
a  less  amount  of  electric  energy.  These  are  the  properties  that 
give  to  the  tungsten  lamp  its  value  over  the  carbon  lamp. 

The  exact  advantage  of  the  tungsten  lamp  has  been  investi- 
gated with  great  care  and  its  behavior  under  general  working  con- 
ditions is  definitely  known.  In  light-giving  properties  where  the 
carbon-filament  lamp  requires  3.1  watts  to  produce  a  candlepower 


310  MECHANICS  OF  THE  HOUSEHOLD 

of  light,  in  the  tungsten  filament  only  1.1  watts  are  necessary 
to  cause  the  same  effect.  The  tungsten  lamp  therefore  gives 
almost  three  times  as  much  light  as  the  carbon  lamp  for  the  same 
energy  expended.  The  manufacturers  aim  to  make  lamps  that 
give  the  greatest  efficiency  for  a  definite  number  of  hours  of  serv- 
ice. It  has  been  agreed  that  1000  working  hours  shall  be  the 
life  of  the  lamps  and  in  that  period  the  filament  should  give  its 
greatest  amount  of  light  for  the  energy  consumed. 

The  Mazda  Lamp. — The  trade  name  for  the  lamp  giving  the 
greatest  efficiency  is  Mazda.  The  term  is  taken  as  a  symbol 
of  efficiency  in  electric  incandescent  lighting.  At  present  the 
Mazda  is  the  tungsten-filament  lamp,  but  should  there  be  found 
some  other  more  efficient  means  of  lighting,  which  can  take  its 
place  to  greater  advantage,  that  will  become  the  Mazda  lamp. 

Candlepower. — The  incandescent  lamps  are  usually  rated  in 
light-giving  properties  by  their  value  in  horizontal  candlepower. 
This  represents  the  mean  value  of  the  light  of  the  lamp  which 
comes  from  a  horizontal  plane  passing  through  the  center  of 
illumination  and  perpendicular  to  the  long  axis  of  the  lamp. 
Candlepower  in  this  connection  originally  referred  to  the  English 
standard  candle  which  is  made  of  spermaceti.  The  standard 
candle  is  0.9  inch  in  diameter  at  the  base,  0.8  inch  in  diameter  at 
the  top  and  10  inches  long.  It  burns  120  grains  of  spermaceti  and 
wick  per  hour.  This  candle  is  not  satisfactory  as  a  standard 
because  of  the  variable  conditions  that  must  surround  its  use. 
The  American  or  International  standard  is  equal  to  1.11  Hefner 
candles.  The  Hefner  candle  (which  is  the  standard  in  con- 
tinental Europe  and  South  American  countries)  is  produced  by  a 
lamp  burning  amylacetate.  This  lamp  consists  of  a  reservoir 
and  wick  of  standard  dimensions  which  gives  a  constant  quan- 
tity of  light.  The  light  from  this  lamp  has  proven  much  more 
satisfactory  as  a  means  of  measurement  of  light  than  the  English 
standard  and  therefore  its  use  has  been  very  generally  adopted. 

The  light  given  out  by  an  incandescent  lamp  is  not  the  same 
in  all  directions.  In  making  comparisons  it  is  necessary  to  define 
the  position  from  which  the  light  of  the  lamps  is  taken.  The 
horizontal  candlepower  affords  a  fairly  exact  means  of  com- 
paring lamps  which  have  the  same  shape  of  filament,  but  for 
different  kinds  of  lamps  it  does  not  give  a  true  comparison.  The 


ELECTRICITY  311 

spherical  candlepower  is  used  to  compare  lamps  of  different  con- 
struction as  this  gives  the  mean  value  at  all  points  of  a  sphere 
surrounding  the  lamp.  The  candlepower  is  measured  at  various 
positions  about  the  lamp  with  the  use  of  a  photometer,  and  the 
mean  of  these  values  is  taken  as  the  mean  spherical  candlepower. 

At  their  best,  carbon-filament  lamps  require  in  electricity 
3.1  w.p.c.  (watts  per  candlepower).  As  the  lamp  grows  old  the 
number  of  watts  per  candle  power  increases,  until  in  very  old 
lamps  the  amount  of  electricity  used  to  produce  a  given  amount 
of  light  may  become  excessively  large.  According  to  a  bulletin 
issued  by  the  Illinois  Engineering  Experiment  Station  on  the 
efficiency  of  carbon-filament  incandescent  lamps,  the  amount  of 
electrical  energy  per  candlepower  varied  from  3.1  w.p.c.,  when 
new,  to  4.2  w.p.c.,  after  burning  800  hours. 

A  common  practice  in  the  use  of  carbon-filament  lamps  is  to 
consider  that  the  period  of  useful  life  ends  at  a  point  where  the 
amount  of  electricity,  per  candlepower,  reaches  20  per  cent,  in 
excess  of  the  original  amount.  This  point  (sometimes  termed 
the  smashing  point)  would  be  reached  after  800  working  hours, 
according  to  the  Illinois  Station,  and  at  about  1000  hours  as 
stated  by  the  bulletins  of  the  General  Electric  Co.  If  a  carbon- 
filament  lamp  burns  for  an  average  period  of  3  hours  a  day  for  a 
year,  it  ought  to  be  replaced. 

The  Edison  screw  base  as  shown  in  Fig.  217  is  now  generally 
used  in  all  makes  of  incandescent  lamps  for  attaching  the  lamp 
to  the  socket.  When  screwed  into  place  this  base  forms  in  the 
socket  the  connections  with  the  supply  wires,  to  produce  a  cir- 
cuit through  the  lamp.  One  end  of  the  filament  is  attached  to  the 
brass  cap  contact,  the  opposite  end  connects  with  the  brass  screw 
shell  of  the  base.  When  the  current  is  turned  on,  the  contact 
made  in  the  switch  is  such  as  to  form  a  complete  circuit  between 
the  supply  wires;  the  voltage  sending  a  constant  current  through 
the  lamp  produces  a  steady  incandescence  of  the  filament. 

In  Fig.  218  is  shown  a  carbon-filament  lamp  attached  to  an 
ordinary  socket.  The  lamp  base  and  socket  are  shown  in  section 
to  expose  all  of  the  parts  that  comprise  the  mechanism.  The  in- 
sulated wires  of  the  lamp  cord  enter  the  top  of  the  socket  and  the 
ends  attach  to  the  binding  screws  A  and  B,  which  are  insulated 
from  each  other  and  form  the  brass  shell  which  encases  the  socket. 


312 


MECHANICS  OF  THE  HOUSEHOLD 


The  lamp  base  is  shown  screwed  into  the  socket,  the  brass  cap 
contact  F  making  connection  at  G;  the  screw  shell  joins  the  socket 
at  D.  To  the  key  S  is  attached  a  brass  rod  R,  on  which  is  fastened 
E,  the  contact-maker.  The  rod  R  passes  through  a  sup- 
portary  frame  which  is  secured  to  the  lamp  socket  at  G.  As 
shown  in  the  figures  the  piece  E  makes  contact  with  a  brass 
spring  attached  to  A,  and  this  completes  a  circuit  through  the 
filament.  The  brass  cap  contact  of  the  lamp  base  makes  con- 
nection at  one  end  of  the  filament  H,  the 
other  end  of  the  filament  K  is  attached  to 
the  brass  screw  shell  of  the  base,  which  in 
turn  connects  with  the  screw  shell  of  the 
socket  and  this  shell  is  connected  with  the 
piece  containing  the  binding  screw  B  by  the 
rod  C  to  complete  the  circuit.  When  the 
key  S  turns,  the  contact  above  E  is  broken 
and  the  lamp  ceases  to  burn. 

Fig.  118  shows  the  use  of  an  adapter 
that  is  sometimes  encountered  in  old  elec- 
tric fixtures,  the  use  of  which  requires  ex- 
planation. Mention  has  already  been  made 
of  the  various  forms  of  lamp  sockets  in  use 
before  the  Edison  base  became  a  standard. 
In  order  to  use  an  Edison  lamp  in  a  socket 
intended  for  another  form  of  base  an  adap- 
ter must  be. employed  to  suit  the  new  base 
to  the  old  socket.  In  the  figure  the  piece 
PI,  is  the  adapter.  This  is  intended  to 
adapt  the  standard  lamp  base  to  a  socket 
that  was  formerly  in  use  on  the  Thompson-Houston  system  of 
electric  lighting.  The  adapter  is  joined  to  the  old  socket  by  the 
screw  at  G  and  the  circuit  formed  as  already  described. 

Lamp  Labels. — For  many  years  all  incandescent  lamps  were 
rated  in  candlepower  and  were  made  in  sizes  8,  16,  32,  etc.,  candle- 
power.  On  the  label  was  printed  the  voltage  at  which  the  lamp 
was  intended  to  operate,  and  also  the  candlepower  it  was  sup- 
posed to  develop.  Thus  110  v.,  16  cp.  indicated  that  when  used 
on  110-volt  circuit,  the  lamp  would  give  16  candlepower  of  light. 
This  label  in  no  way  indicated  the  amount  of  energy  expended. 


FIG,    218. — Section  of  a 
lamp  base  and  socket. 


ELECTRICITY  313 

With  the  development  of  the  more  efficient  filaments  came  a 
tendency  to  label  lamps  in  the  amount  of  energy  consumed.  This 
has  resulted  in  all  lamps  being  labeled  to  show  the  voltage  of  the 
circuit  suited  to  the  lamp,  and  the  watts  of  electricity  consumed 
when  working  at  that  voltage.  At  present  a  lamp  label  may  be 
marked  110  v.,  40  w.,  which  indicates  that  it  is  intended  to 
develop  its  best  performance  at  110  volts  and  will  consume  40 
watts  at  that  voltage. 

Commercial  lamps  are  now  manufactured  in  sizes  of  10,  15, 
25,  40,  60,  75,  and  100  watts  capacity  for  ordinary  use.  Of  these 
the  40-watt  lamp  probably  fulfills  the  greatest  number  of  con- 
ditions and  is  most  commonly  used.  Besides  these  there  are 
the  high-efficiency  lamps  of  the  gas-filled  variety  that  are  made 
in  larger  sizes  and  the  miniature  lamps  in  great  variety.  All 
are  labeled  to  show  the  volts  and  the  watts  consumed. 

Illumination. — The  development  of  high-efficiency  lamps  has 
caused  a  radical  change  in  the  methods  of  illumination.  With 
cheaper  light  came  the  desire  to  more  nearly  approximate  the 
effect  of  daylight  in  illumination.  This  has  brought  into  use 
indirect  illumination,  in  which  the  light  from  the  lamp  is  diffused 
by  reflection  from  the  ceiling  and  walls  of  the  room.  Illuminating 
engineering  is  now  a  business  that  has  to  do  with  placing  of  lamps 
to  the  greatest  advantage  in  lighting  any  desired  space.  In 
large  and  complicated  schemes  of  lighting  professional  services 
are  necessary,  but  in  household  lighting  the  required  number  of 
lamps  for  the  various  apartments  are  almost  self-evident.  The 
lighting  of  large  rooms,  however,  requires  thoughtful  consider- 
ation and  in  many  cases  the  only  definite  solution  of  the  prob- 
lem is  that  of  calculation. 

The  Foot-candle. — The  amount  of  illumination  produced  over 
a  given  area  depends  not  only  on  the  number  of  lamps  and  their 
candlepower,  but  upon  their  distribution  and  the  color  of  the 
walls  and  furnishings.  In  the  calculation  of  problems  in  illumina- 
tion, units  of  measure  are  necessary  to  express  the  amount  of 
light  that  will  be  furnished  at  any  point  from  its  source.  The 
units  adopted  for  such  purposes  are  the  foot-candle  and  the 
lumen. 

The  Lumen. — A  light  giving  1  candlepower,  placed  in  the 
center  of  a  sphere  of  1  foot  radius  illuminates  a  sphere,  the  area 


314  MECHANICS  OF  THE  HOUSEHOLD 

of  which  is  4  X  3.1416  or  12.57  square  feet.  The  intensity  of 
light  on  each  square  foot  is  denoted  as  a  candle-foot.  The 
candle-foot  is  the  standard  of  illumination  on  any  surface.  The 
quantity  of  light  used  in  illuminating  each  square  foot  of  the 
sphere  is  called  a  lumen*.  A  light  of  1  candlepower  will  there- 
fore produce  an  intensity  of  1  candle-foot  over  12.57  square 
feet  and  give  12.57  lumens.  Therefore,  if  all  of  the  light  is 
effective  on  a  plane  to  be  illuminated,  a  lamp  rated  at  400  lumens 
would  light  an  area  of  400  square  feet  to  an  average  intensity  of 
1  candle-foot. 

To  find  the  number  of  lamps  required  for  lighting  any  space, 
the  area  in  square  feet  is  multiplied  by  the  required  intensity 
in  foot-candles,  to  obtain  the  total  necessary  lumens,  and  the 
amount  thus  obtained  is  divided  by  the  effective  lumens  per 
lamp. 

The  bulletins  of  the  Columbia  Incandescent  Lamp  Works 
gives  the  following  method  of  calculating  the  number  of  lamps 
required  to  light  a  given  space: 

SXI 

Number  of  lamps  =  ^^ — -. , —  — r — 

Effective  lumens  per  lamp 

S   (square  feet)    X    /    (required  illumination  in  foot- 
candles)  =  total  lumens. 

The  total  lumens  divided  by  the  number  of  effective  lumens 
per  lamp  gives  the  number  of  lamps  required.  In  using  the 
formula  the  effective  lumens  per  lamp  is  taken  from  the  follow- 
ing table: 

Watts  per  lamp 25       40       60     160     150       250 

Effective  lumens  per  lamp  95     160     250     420     630     1090 
Lumens  per  watt 3.8     4.0     4.2     4.2     4.2       4.3 

The  size  of  the  units  is  a  matter  of  choice  since  six  400-lumen 
units  are  equal  to  four  600-lumen  units  in  illuminating  power, 
etc.  In  deciding  upon  the  proper  size  of  lamps  to  use,  consider- 
ation must  be  taken  of  the  outlets  if  the  building  is  already  wired. 
In  general  the  fewest  units  consistent  with  good  distribution  will 
be  the  most  economical.  The  table  shows  the  lumens  effective 
for  ordinary  lighting  with  Mazda  lamps  and  clear  high-efficiency 
reflectors  with  dark  walls  and  ceiling.  Where  both  ceiling  and 
walls  are  very  light  these  figures  may  be  increased  by  25  per  cent. 


ELECTRICITY 


315 


To  illustrate  the  use  of  the  table,  take  an  average  room  16  by 
24  to  be  lighted  with  Mazda  lamps  to  an  intensity  of  3.5  foot- 
candles.  If  clear  Holoplane  reflectors  are  used,  the  values  for 
lumens  effective  on  the  plane  may  be  increased  10  per  cent, 
due  to  reflection  from  fairly  light  walls.  The  lamps  in  this  case 
are  to  be  of  the  40-watt  type  which  in  the  table  are  rated  at  160 
lumens.  To  this  amount  10  per  cent,  is  added  on  account  of  the 
reflectors  and  walls.  This  data  applied  to  the  formula  gives: 

s  =  16  by  24  feet 

/  =  3.5 

Lumens  per  lamp  =  160 

(16  X  24)  X  3.5 

~~       ~  =     eight  40-watt  lamps. 


ENCLOSING    UNIT 


SEMI-  INDIRECT 
UNIT 

FIG.  219. 


COLOR   MATCHING  UNIT 


Reflectors. — The  character  and  form  of  reflectors  have  much 
to  do  with  the  effective  distribution  of  the  light  produced  by 
the  lamp.  The  most  efficient  form  of  reflectors  are  made  of 
glass  and  designed  to  project  the  light  in  the  desired  direction. 
The  illustration  in  Fig.  219,  marked  open  reflector,  shows  the 
characteristic  features  of  reflectors  designed  for  special  purposes. 
They  are  made  of  prismatic  glass  fashioned  into  such  form  as 
will  produce  the  desired  effect  and  at  the  same  time  transmit 


316  MECHANICS  OF  THE  HOUSEHOLD 

and  diffuse  a  part  of  the  light  to  all  parts  of  the  space  to  be 
lighted.  The  greater  portion  of  the  light  is  sent  in  the  direction 
in  which  the  highest  illumination  is  desired.  The  reflectors 
are  made  to  concentrate  the  light  on  a  small  space  or  to  spread 
it  over  a  large  area  as  is  desired.  They  are,  therefore,  designated 
as  intensive  or  extensive  reflectors  and  made  in  a  variety  of  forms. 

Choice  of  Reflector. — Where  the  light  from  a  single  lamp  must 
spread  over  a  relatively  great  area,  it  is  advisable  to  use  an 
extensive  form  of  reflector.  This  reflector  is  applicable  to  general 
residence  lighting,  also  uniform  lighting  of  large  areas  where 
low  ceilings  or  widely  spaced  outlets  demand  a  wide  distribution 
of  light.  Where  the  area  to  be  lighted  by  one  lamp  is  smaller, 
the  intensive  reflector  is  used.  Such  cases  include  brilliant 
local  illumination,  as  for  reading  table's,  single-unit  lighting  or 
rooms  with  high  ceilings  as  pantries  or  halls. 

Where  an  intense  light  on  a  small  area  directly  below  the 
lamp  is  desired,  a  focusing  reflector  is  used.  The  diameter  of  the 
circle  thus  intensely  lighted  is  about  one-half  the  height  of  the 
lamp  above  the  plane  considered.  Focusing  reflectors  are  used 
in  vestibules  or  rooms  of  unusually  high  ceilings. 

Type  Height  above  plane  to  be  lighted 

Extensive %  D 

Intensive H  D 

Focusing %  D 

D  =  distance  between  sides  of  room  to  be  illuminated. 

The  various  other  fixtures  of  Fig.  219  that  are  designated 
as  reflectors  are  in  some  cases  only  a  means  of  diffusion  of  light. 
In  the  use  of  the  high-efficiency  gas-filled  lamps  the  light  is  too 
bright  to  be  used  directly  for  ordinary  illumination.  When  these 
lamps  are  placed  in  opal  screens  of  the  indirect  or  the  semi- 
indirect  form  the  light  produced  for  general  illumination  is 
very  satisfactory.  Considerable  light  is  lost  in  passing  through 
the  translucent  glass  but  this  is  compensated  by  the  use  of  the 
high-efficiency  lamps  and  the  general  satisfaction  of  light  dis- 
tribution. 

Lamp  Transformers. — Lamps  of  the  Mazda  type,  constructed 
to  work  at  the  usual  commercial  voltages,  are  made  in  low-power 
forms  to  consume  as  little  as  10  watts;  but  owing  to  the  difficulty 
of  arranging  a  suitable  filament  for  the  smaller  sizes  of  lamps, 


ELECTRICITY  317 

less  voltage  is  required  to  insure  successful  operation.  The 
lamps  for  this  purpose  are  of  the  type  used  in  connection  with 
batteries  and  require  1  or  more  volts  to  produce  the  desired 
illumination.  When  these  little  lamps  are  used  on  a  commercial 
circuit,  the  reduction  of  the  voltage  is  accomplished  by  small 
transformers,  located  in  the  lamp  socket.  The  operating  prin- 
ciple and  further  use  of  the  transformers  will  be  explained  later 
under  doorbell  transformers.  The  lamp  transformer,  although 
miniature  in  design,  is  constructed  as  any  other  of  its  kind  but 
designed  to  reduce  the  usual  voltage  of  the  circuit  to  6  volts  of 
pressure.  The  socket  is  that  intended  for  the  use  of  the  Mazda 
automobile  lamp  giving  2  candlepower.  This  lamp  used  with 
electricity  at  the  average  rate  per  kilowatt  can  be  burned  for 
10  hours  at  less  than  half  a  cent.  In  bedrooms,  sickrooms  and 


D 

FIG.  220. — Miniature  lamp  transformer  complete  and  the  parts  of  which  it  is 

composed. 

other  places  where  a  small  amount  of  light  is  necessary  but  where 
a  considerable  quantity  is  objectionable,  the  miniature  lamp 
transformer  serves  an  admirable  purpose  in  adapting  the 
voltage  of  the  commercial  alternating  circuit  to  that  required 
for  lamps  of  small  illuminating  power.  Such  a  transformer  is 
shown  in  Fig.  220. 

The  figure  shows  in  A  the  assembled  attachment  with  the  lamp 
bulb  in  place.  The  part  B,  the  transformer,  changes  the  line 
voltage  to  that  of  a  battery  lamp.  A  line  voltage  of  110  may  be 
transformed  to  suit  a  6-volt  miniature  lamp.  The  parts  C  and 
D  compose  the  screw  base  and  the  cover,  in  which  is  fitted  the 
transformer  B. 

Units  of  Electrical  Measurement. — The  general  application 
of  electricity  has  brought  into  common  use  the  terms  necessary  in 
its  measurement  and  units  of  quantity  by  which  it  is  sold.  The 
volt,  ampere  and  ohm  are  terms  that  are  used  to  express  the  con- 


318  MECHANICS  OF  THE  HOUSEHOLD 

ditions  of  the  electric  circuit;  the  watt  and  the  kilowatt  are  units 
that  are  employed  in  measuring  its  quantity  in  commercial  usage. 
The  use  of  these  units  in  actual  problems  is  the  most  satis- 
factory method  of  appreciating  their  application. 

As  already  explained  the  volt  is  the  unit  of  electric  pressure 
which  causes  current  to  be  sent  through  any  circuit.  The  elec- 
tric circuits  of  houses  are  intended  to  be  under  constant  voltage — 
commonly  110  or  220 — but  the  voltage  may  be  any  amount  for 
which  the  generating  system  is  designed.  Independent  lighting 
systems  such  as  are  used  in  house-lighting  plants — to  be  de- 
scribed later — commonly  employ  32  volts  of  electric  pressure. 

Opposed  to  the  effect  of  the  volts  of  electromotive  force  is 
the  resistance  of  the  circuit,  which  is  measured  in  ohms.  Re- 
sistance has  been  called  electric  friction;  it  expresses  itself  as 
heat  and  tends  to  diminish  the  flow  of  current.  Every  circuit 
offers  resistance  depending  on  the  length,  the  kind  and  the  size 
of  wire  used.  Since  the  wires  of  commercial  lighting  systems 
are  made  of  copper,  it  can  be  said  that  the  resistance  of  the 
circuit  increases  as  the  size  of  the  conducting  wire  decreases. 
In  large  wires  the  resistance  is  small  but  as  the  size  of  the  wire 
is  reduced  the  resistance  is  increased.  A  long  attachment 
cord  of  a  flat-iron,  may  offer  sufficient  resistance  to  prevent 
the  iron  from  heating  properly. 

The  ampere  is  the  unit  which  measures  the  amount  of  current. 
The  amperes  of  current  determine  the  rate  at  which  the  electric- 
ity is  being  used  in  any  circuit.  The  wires  of  a  house  must  be 
of  a  size  sufficient  to  carry  the  necessary  current  without  heat- 
ing. Any  house  wire  which  becomes  noticeably  warm  is  too  small 
for  the  current  it  carries  and  should  be  replaced  by  one  that  is 
larger. 

The  watt  is  the  unit  of  electric  quantity.  The  quantity  of 
electricity  being  used  in  any  circuit  is  the  product  of  the  volts 
of  pressure  and  amperes  of  current  flowing  through  the  wires. 
The  amount  of  current — in  amperes — sent  through  the  circuit  is 
the  direct  result  of  the  volts  of  pressure ;  the  quantity  of  electricity 
is  therefore  the  product  of  these  two  factors.  A  25-watt  lamp  on 
a  circuit  of  110  volts  uses  0.227  ampere  of  current. 

25  watts    =    110  volts    X    0.227  amperes. 


ELECTRICITY  319 

Ten  such  lamps  use 

10    X    0.227  amperes   =   2.27  amperes. 

The  product  of  110  volts  and  2.27  amperes  is  250  watts. 

In  order  to  express  quantity  of  energy,  it  is  necessary  to  state 
the  length  of  time  the  energy  is  to  act  and  originally  the  watt 
represented  the  energy  of  a  volt-ampere  for  one  second.  For 
commercial  purposes  this  quantity  is  too  small  for  convenient  use 
and  the  hour  of  time  was  taken  instead.  The  watt  of  commercial 
measurement  is  the  watt-hour  and  in  the  purchase  of  electricity 
the  watt  is  always  understood  as  that  quantity. 

Even  as  a  watt-hour  the  measure  is  so  small  as  to  require  a 
large  number  to  express  ordinarj^  amounts  and  a  still  larger  unit 
of  1000  watt-hours  or  the  kilowatt-hour  was  adopted  and  has  be- 
come the  accepted  unit  of  commercial  electric  measurement.  Just 
as  a  dollar  in  money  conveniently  represents  1000  mills  so  does  a 
kilowatt  of  electricity  represent  a  convenient  quantity. 

In  the  purchase  of  electricity,  the  consumer  pays  a  definite 
amount,  say  10  cents  per  kilowatt.  This  represents  an  exact 
quantity  of  energy,  that  may  be  expended  in  light,  in  heat,  or  in 
the  generation  of  power,  all  of  which  may  be  expressed  as  definite 
quantities. 

As  light,  it  indicates  in  the  electric  lamp  the  number  of  candle- 
power-hours  that  may  be  obtained  for  10  cents.  At  this  rate 
a  single  watt  costs  0.01  cent  an  hour.  A  25-watt  electric  lamp  will 
therefore  cost  0.25  (J^)  cent  for  each  hour  of  use;  a  60-  watt 
lamp  costs  0.6  cent  per  hour;  the  ten  25-watt  lamp  mentioned 
above  using  250  watts  costs  2.5  cents  per  hour. 

As  heat,  it  is  expressed  in  English-speaking  countries  as  Brit- 
ish thermal  units,  1  kilowatt-hour  representing  3412  B.t.u.  per 
hour.  One  cent's  worth  of  electricity  at  the  rate  given  yields 
341.2  B.t.u.  of  heat. 

As  power,  it  represents  an  exact  amount  of  work.    So  expressed, 

a  watt  represents  wj    horsepower;  therefore  a  kilowatt  is  repre- 


sented in  power  as  ~^r     =  1.3  horsepower.     Since  the  kilowatt 


purchased  for  10  cents  is  a  kilowatt-hour,  the  equivalent  horse- 
power is  for  the  same  length  of  time.  At  the  assumed  rate,  10 
cents  buys  1.3  horsepower  for  one  hour.  When  used  as  work 


320 


MECHANICS  OF  THE  HOUSEHOLD 


it  represents  2,544,000  foot-pounds  or  255,400  foot-pounds  of 
work  for  1  cent.  This  work  when  expended  in  a  motor,  to 
do  the  family  washing  or  perform  any  other  household  drudgery, 
represents  the  greatest  value  to  be  derived  from  its  use.  A  %- 
horsepower  motor  is  amply  large  to  operate  a  family  washing 
machine.  Even  though  the  motor  is  only  50  per  cent,  efficient 
its  cost  of  operation  is  less  than  7  cents  per  hour. 

Miniature  Lamps. — Miniature  electric  lamps  include  all  that 
are  not  used  for  general  illuminating  purposes.  The  term  applies 
more  particularly  to  the  form  of  the  base  than  to  the  voltage 
or  candlepower  of  the  filament.  There  are  three  general  classes 
of  these  lamps :  candelabra  and  decorative,  that  operate  on  light- 
ing circuits  of  100  to  130  volts  and  are  usually  intended  for  deco- 


Candelabra  screw  Minature  screw  Double-contact  bayo-  Single-contact  bayo- 
base  base  net  candelabra  base     net  candelabra  base 

FIG.  221. — Miniature  lamp  bases. 

rative  purposes;  general  battery  lamps  used  for  flash  lights;  and 
lamps  for  automobiles  and  electric-vehicle  service. 

The  term  miniature  lamp  applies  more  particularly  to  the 
base  than  to  the  voltage  or  candlepower.  The  style  of  base  is 
characteristic  of  the  service  for  which  the  lamp  is  designed  rather 
than  the  size  or  number  of  watts  consumed.  There  are  two 
general  styles  of  bases:  the  screw  type  of  the  Edison  construc- 
tion of  which  there  are  two  sizes;  and  the  bayonet  type  of  which 
there  are  two  styles  of  construction. 

Bases  for  miniature  lamps  are  made  in  form  to  suit  the  condi- 
tions of  their  use.  The  styles  at  present  are  shown  in  Fig.  221. 
Of  these  the  screw  bases  at  the  left  are  those  attached  to  small 
flash-lamp  bulbs  and  others  of  the  smaller  sizes  of  lamps.  The 
two  at  the  right  of  the  figure  are  the  bayonet  style  used  under 
conditions  not  suited  to  the  screw  contact.  In  the  case  of  auto- 
mobile lamps  and  in  places  where  vibration  will  cause  loss  of 
contact  the  bayonet  base  is  generally  in  use.  The  lamp  is  held 
in  place  by  the -projecting  lugs  that  engage  with  openings  in  the 


ELECTRICITY 


321 


socket  and  kept  in  place  by  the  pressure  of  a  spring.  The 
contact  with  the  lamp  filament  is  made  by  two  terminals  that 
make  connection  directly  with  the  terminals  of  the  lamp  filament. 
The  single  contact  base  is  kept  in  place  similarly  to  that  of  the 
other  but  makes  a  single  contact  at  the  end  of  the  socket  while 
the  other  but  makes  a  single  contact  at  the  end  of  the  socket 
while  the  circuit  is  completed  through  the  pressure  exerted  be- 
tween the  projecting  lugs  and  the  socket. 

Effect  of  Voltage  Variations. — Voltage  variation  may  be  tem- 
porary, due  to  changing  load  in  the  circuit,  or  in  constantly 
overloaded  circuits  the  voltage  may  be 
constantly  below  normal.  The  change 
in  electric  pressure  affects  in  a  consider- 
able degree  the  amount  of  light  given 
by  the  lamp.  As  an  example,  a  5  per 
cent,  drop  from  the  normal  voltage  will 
cause  a  decrease  of  31  per  cent,  in  the 
amount  of  light  given.  This  means 
that  if  a  lamp  is  working  on  a  circuit 
of  110  volts  and  the  voltage  from  any 
cause  were  to  drop  to  104^  volts,  the 
light  would  decrease  6.8,  almost  7 
candlepower.  Drop  in  voltage  may  also 
be  due  to  the  resistance  of  wires  that 
are  too  small  for  the  service.  Lamps 
attached  to  such  a  circuit  will  constantly 
burn  dim. 

Turn-down  Electric  Lamp  s. — T  h  e 
ordinary  incandescent  lamp  lacks  the 
flexibility  of  gas  and  oil  lamp,  in  that 
the  amount  of  light  cannot  be  varied 
at  will.  This  feature  is  attained  in  the 
electric  turn-down  lamp  either  by  resistance  added  to  the  lamp 
circuit  or  by  the  use  of  two  separate  filaments  in  a  single  globe; 
one  of  ordinary  lamp  size  and  the  other  of  such  size  that  it  con- 
sumes only  a  fraction  as  much  energy  as  the  normal  lamp. 

Turn-down  lamps  of  the  latter  form  are  made  in  several  styles, 
the  chief  points  of  difference  being  in  the  method  of  changing 
the  contact  from  the  high-  to  the  low-power  filament.    In  Fig.  222 
21 


FIG.  222. — Sectional  view 
of  a  "turn-down"  lamp 
socket. 


322  MECHANICS  OF  THE  HOUSEHOLD 

a  sectional  view  shows  the  "  pull-string  "  form  of  lamp  in  which 
the  parts  are  exposed.  The  long  filament  H  and  the  smaller  one 
L  represent  two  individual  lamps  of  different  lighting  power. 
The  change  in  light  is  made  from  one  to  the  other  by  pulling  the 
string  which  is  attached  to  a  switch  in  the  socket  and  which 
changes  the  contact  to  send  the  current  through  the  filament 
giving  the  desired  amount  of  light.  The  figure  shows  a  carbon- 
filament  lamp,  but  tungsten  lamps  are  made  to  accomplish  the 
same  purpose.  The  difficulty  of  manufacturing  a  1-candlepower 
tungsten  lamp  for  direct  operation  on  a  110-volt  circuit  requires 
the  filaments  to  work  in  series.  The  figure  is  arranged  on  the 
same  plan  as  for  a  tungsten  lamp. 

The  lamp  base  when  screwed  into  the  socket  makes  contact 
with  the  two  service  wires  of  the  circuit  at  A  and  at  E,  which 
are  part  of  the  screw  base.  To  light  the  lamp  the  current  is 
switched  on  as  in  any  lamp.  The  current  enters  at  A  and  passes 
down  the  connecting  piece  to  the  contact  B.  The  piece  B  is 
moved  by  the  cord  to  light  either  the  large  or  the  small  filament. 
In  the  position  shown  the  current  enters  the  small  filament  at  C 
and  in  order  to  complete  the  circuit  to  E  must  traverse  both  the 
large  and  the  small  filament.  The  resistance  of  the  small  fila- 
ment is  such  that  the  passing  current  raises  it  to  a  temperature 
of  incandescence  but  the  large  filament  does  not  heat  sufficiently 
to  give  an  appreciable  amount  of  light.  When  the  cord  is  pulled 
to  light  the  large  filament,  the  contact  is  made  at  D  and  the 
current  passes  directly  through  the  large  filament  to  complete 
the  circuit  at  E. 

Turn-down  lamps  are  especially  adapted  to  the  home.  Their 
use  in  a  child's  bedroom  or  sick  chamber  is  a  great  convenience. 
The  lamps  are  often  constructed  with  a  long-distance  cord  extend- 
ing from  a  fixture  to  the  bedside.  By  this  means  a  dim  or  bright 
light  is  given  as  desired,  with  the  least  inconvenience.  Turn- 
down lamps  are  made  in  a  variety  of  sizes.  The  large  filaments 
are  arranged  to  give  8,  16,  and  32  candlepower.  With  the  8- 
candlepower  lamp  the  small  filament  gives  %  candlepower  and 
with  the  16-  and  32-candlepower  the  small  filament  gives  1 
candlepower. 

With  the  lamps  described,  the  variation  in  amount  of  light 
is  attained  by  changing  the  contacts,  to  bring  into  action  fila- 


ELECTRICITY 


323 


ments  of  different  resistances.  They  admit  of  only  two  changes, 
either  the  lamp  burns  at  full  capacity  or  at  the  least  light  the 
lamp  will  give.  The  heat  liberated  by  the  large  filament,  when 
the  small  light  is  in  use,  takes  place  inside  the  lamp  globe. 

The  Dim-a-lite. — In  another  form  of  turn-down  lamp  the 
change  in  amount  of  light  is  produced  by  external  resistance  in 
the  circuit.  The  resistance  is  furnished  by  a  coil  of  wire  which  is 
enclosed  in  a  special  lamp  socket.  It  possesses  the  advantage 
as  a  turn-down  lamp  in  a  number  of  changes  of  light.  The  added 
resistance  in  a  socket  decreases  the  flow  of  current  and,  therefore, 
the  filament  gives  less  light.  The  resistance  wire  is  divided  into 
a  number  of  sections  and  contact  with  the  ter- 
minals of  these  sections  decreases  the  light  with 
each  addition  of  resistance.  The  heat  generated 
in  the  resistance  coils  is  dissipated  by  the  brass 
covering  of  the  socket. 

An  illustration  of  a  turn-down  lamp  using  a 
separate  resistance  is  that  of  Fig.  223,  known 
commercially  as  the  Dim-a-lite,  which  is  an  ex- 
cellent example.  The  Dim-a-lite  attachment  is 
a  lamp  socket  in  which  is  enclosed  a  miniature 
rheostat  or  resistance  unit.  The  lamp,  when 
placed  on  the  Dim-a-lite,  makes  electrical  con- 
tact as  in  an  ordinary  socket  but  with  the 
difference  that  in  series  with  the  lamp  filament  The  resistance 
is  the  rheostat,  by  means  of  which  additional  re-  *ype  ,?*  "turn- 

down     lamp. 

sistance  may  be  added  to  change  the  current  flow- 
ing in  the  lamp.  The  rheostat  is  so  arranged  that  contact  may  be 
made  at  four  different  points  in  the  resistance  coil,  through  which 
the  electricity  may  be  varied  from  100  to  20  per  cent,  of  the 
normal  quantity.  The  resistance  in  any  case  permits  current  to 
pass  through  the  filament  in  amounts  of  70,  30  and  20  per  cent,  of 
the  normal  amount.  In  use,  the  variation  is  made  by  pulling  one 
string  to  add  resistance  and  thus  dim  the  light;  or  by  pulling  the 
other  string,  the  resistance  is  decreased  and  more  electricity 
passes  through  the  filament  to  produce  a  brighter  light.  The 
quantity  of  light  given  out  by  the  filament  does  not  vary  in  the 
ratio  of  the  added  resistance  but  a  variable  light  is  obtained  at 
the  expense  of  a  small  amount  of  electricity  which  is  changed 


324 


MECHANICS  OF  THE  HOUSEHOLD 


2 


/2 


into  heat.     When  the  light  is  burning  at  its  dimmest  only  20  per 

cent,  of  the  normal  current  is  used.     Under  this  condition  the 

light  given  out  by  filament  does  not  express  the  high  efficiency 

attained  when  the  lamp  is  burning  at  its  full  power  but  it  does 
give  a  convenient  form  of  light  regulation  with  the 
minimum  waste  of  energy. 

Gas-filled  Lamps.—  Until  1913  the  filaments  of 
all  Mazda  lamps  operated  in  a  vacuum.  The  vacuum 
serving  the  purpose  of  preventing  oxidation  and  at 
the  same  time  it  reduced  the  energy  loss  to  the 
least  amount.  It  was  found,  however,  under  some 
conditions  of  construction  that  lamps  filled  with 
inert  gas  gave  a  higher  efficiency  and  more  satisfac- 
w  &t  tory  service  than  those  of  the  vacuum  type.  In  this 

Mazda  B  construction,  the  filament  is  operated  at  a  tempera- 
ture  mucn  higher  than  that  of  the  vacuum  lamp 
and  as  a  consequence  gives  light  at  a  less  cost  per 

candlepower.     Mazda  vacuum  lamps  are  now  designated  by  the 

General  Electric  Co.  as  Mazda  B  lamps,  Fig.  224,  and  those  of 

the  gas-filled  variety,  Fig.  225,  are  designated  as  Mazda  C  lamps. 
The  filaments  of  the  gas-filled  lamps  are  intensely  brilliant  and 

where  they  come  within  the  line  of  vision  should  be  screened  from 

the  eyes.     The  high  efficiency  of  these  lamps 

permit  the  use  of  opal  shades  to  produce  a  de- 

sired illumination  at  a  rate  of  cost  that  com- 

pares favorably  with  the  unscreened  light  of  the 

vacuum  lamps. 

Daylight  Lamps.  —  The  color  of  the  light  from 

an  incandescent  electric  lamp  depends  on  the 

temperature  of  the  filament.     In  the  case  of  the 

gas-filled  Mazda  lamp  the  high  filament  tem- 

perature produces  a  light  that  differs  markedly 

from  the  vacuum  lamps  in  that  it  contains  a 

greater  amount  of  blue  and  green  rays.     It  is 

therefore  possible  to  produce  light  that  is  the 

same  as  average  daylight.     Gas-filled  lamps  with 

globes  colored  to  produce  light  of  noonday  quality  are  produced 

at  an  expenditure  of  1.2  watts  per  candlepower. 

In  the  matching  of  colors,  it  should  be  kept  in  mind  that  the 


FIG.  225.—  750- 
scaie). 


ELECTRICITY  325 

tint  of  any  color  is  influenced  by  the  kind  of  light  by  which  it  is 
viewed.  Colors  matched  by  ordinary  incandescent  light  con- 
taining a  large  percentaga  of  red  rays  cannot  produce  the  same 
effect  when  the  same  articles  are  seen  in  light  of  different 
quality.  The  daylight  lamps  are  therefore  intended  to  be  used 
under  conditions  that  require  daylight  quality. 

Miniature  Tungsten  Lamps. — The  wonderful  light-giving  prop- 
erties of  tungsten  has  made  possible  the  use  of  miniature  in- 
candescent lamps  for  an  almost  infinite  variety  of  usages.  The 
miniature  lamps  are  similar  in  action  to  other  incandescent  elec- 
tric lamps  except  that  they  are  operated  on  voltages  lower  than 
is  used  on  commercial  circuits.  When  used  on  commercial 
circuits,  incandescent  tungsten  lamps  of  less  than  10  watts 
capacity  require  filaments  that  are  too  delicate  to  withstand  the 
conditions  of  ordinary  use.  The  properties  of  tungsten  are  such 
that  the  passage  of  only  a  small  amount  of  current  is  required 
to  render  the  filament  incandescent.  In  the  case  of  a' 110- volt 
circuit,  a  10- watt  lamp  requires  only  0.09+  ampere  to  produce 
the  desired  incandescence.  It  will  be  remembered  that  the  watt 
is  a  volt-ampere  and  the  10-watt  lamp  will  then  require 

110  volts  X  0.09  +  ampere  =  10  watts. 

Since  10-watt  lamps  are  the  smallest  units  that  may  be  used 
on  110- volt  circuits,  their  employment  in  smaller  sizes  must  be 
such  as  will  give  more  stable  filaments.  This  is  possible  when  the 
lamps  are  used  at  lower  voltage.  A  10-watt  lamp  on  a  10-volt 
circuit  will  require  an  ampere  of  current. 

10  volts  X  1  ampere  =  10  watts. 

A  filament  suitable  for  an  ampere  of  current  is  shorter  and 
heavier  than  that  of  the  110- volt  lamp  and  therefore  furnishes  a 
good  form  of  construction.  Still  lower  voltages  may  be  used 
with  filaments  suited  to  the  quantity  of  light  desired. 

In  the  case  of  battery  lamps  that  are  intended  to  operate  on  1 
or  more  volts,  the  filaments  are  made  in  size  and  length  to  suit 
the  condition  of  action.  In  all  cases  the  product  of  the  volts  and 
amperes  give  the  capacity  of  the  lamp  in  watts. 

Miniature  lamps  are  ordinarily  marked  to  show  the  voltage  on 
which  they  are  intended  to  operate.  A  6-volt  battery  lamp  is 


326  MECHANICS  OF  THE  HOUSEHOLD 

intended  to  be  used  with  a  primary  battery  of  four  to  six  cells  de- 
pending on  the  condition  of  usage,  or  three  cells  of  storage  bat- 
tery, each  cell  of  which  gives  2  volts  of  pressure. 

Flash  Lights. — These  are  portable  electric  lamps  composed  of 
a  miniature  incandescent  bulb,  which  with  one  or  more  dry  cells 
are  enclosed  in  a  frame  to  suit  the  purpose  of  their  use.  They  are 
made  in  pocket  sizes  or  in  form  to  be  conveniently  carried  in  the 
hand  and  are  convenient  and  efficient  lamps  wherever  a  small 
amount  of  light  is  required  for  a  short  time.  The  electricity  for 
operating  the  lamp  is  supplied  by  a  battery  of  dry  cells  (to  be 
described  later),  or  by  a  single  dry  cell.  In  each  case  the  in- 
candescent bulb  is  suited  to  the  voltage  of  the  battery. 

In  replacing  the  bulbs  care  must  be  taken  to  see  that  the  volt- 
age is  that  suited  to  the  battery.  The  voltage  is  usually  stamped 
on  the  lamp  base  or  marked  on  the  bulb.  In  case  a  lamp  in- 
tended for  a  single  cell  is  used  with  a  battery  of  three  or  four 
cells,  the  lamp  filament  will  soon  be  destroyed.  The  reverse 
will  be  true  should  a  lamp  intended  for  a  battery  be  used  with  a 
single  cell.  The  single  cell  giving  not  much  more  than  a  volt 
of  electromotive  force  will  not  send  sufficient  current  through 
the  lamp  filament  to  render  it  incandescent. 

The  Electric  Flat-iron. — The  changes  that  have  been  made  in 
domestic  appliances  by  the  extended  use  of  electricity  have 
brought  many  innovations  but  none  are  more  pronounced  than 
the  improvements  made  in  the  domestic  flat-iron.  It  was  the 
first  of  the  household  heating  devices  to  receive  universal  recogni- 
tion and  its  place  as  a  domestic  utility  is  firmly  established. 

The  relatively  high  cost  of  heat  as  generated  through  electric 
energy  is  in  a  great  measure  counterbalanced  in  the  flat-iron  by 
high  efficiency  in  its  use.  In  the  electric  iron,  the  heat  is  de- 
veloped in  the  place  where  it  can  be  used  to  the  greatest  advan- 
tage, and  transmitted  to  the  face  of  the  iron  with  but  very  little 
loss.  Because  of  this  direct  application  the  cost  of  operation  is 
but  slightly  in  excess  of  the  other  methods  of  heating. 

The  electric  flat-iron  has  now  become  a  part  of  the  equipment 
of  every  commercial  laundry,  where  electricity  can  be  obtained 
at  a  reasonable  rate.  The  popularity  of  the  electric  iron  is  due 
to  its  cleanliness  and  to  the  increased  amount  of  work  that  may 
be  accomplished  through  its  use.  Because  of  the  time  saved  in 


ELECTRICITY 


327 


changing  irons  and  the  comfort  of  the  room  by  reason  of  its  lower 
temperature,  a  sufficiently  greater  amount  of  work  is  accom- 
plished to  more  than  compensate  for  the  greater  cost  of  heat.l 

The  electric  current  is  conducted  to  the  flat-iron  from  the 
house  circuit  by  wires  made  into  the  form  of  a  flexible  cord. 
The  cord  attaches  to  the  electric-lamp  fixture  by  a  screw-plug 
and  connects  with  the  iron  by  a  special  attachment  piece  as  in- 
dicated at  P  and  R  in  Fig.  226.  Connection  is  made  to  an  in- 
candescent lamp  socket  at  any  convenient  place.  The  only  pre- 
caution necessary  in  attaching  the 
iron  is  to  see  that  the  fuse  and  the 
wires,  which  form  the  circuit,  are  of 
size  sufficient  to  transmit  the  amount 
of  current  the  iron  is  rated  to  use. 
As  explained  later,  the  fuse  which  is 
a  part  of  every  electric  house  circuit, 
and  the  conducting  wires  which  form 
the  heater  circuit,  must  be  sufficient 
in  size  to  transmit  the  necessary  cur- 
rent without  material  heating. 

The  cord  connects  with  the  socket 
at  P,  and  the  current  turned  on. 
It  is  attached  with  the  iron  by  a 
piece  R,  made  of  non-conducting  and 
heat-resisting  material  and  arranged 
to  make  contact  with  the  heater 
terminals  by  two  brass  plugs  that 
are  insulated  from  the  body  of  the 
iron  and  afford  easy  means  of  making 
electric  contact.  The  contact  plugs 
are  shown  in  Fig.  227.  To  make  electric  connection,  the  con- 
tact piece  is  simply  pushed  over  the  plugs,  where  it  is  held  in 
place  by  friction.  Instructions  which  accompany  a  flat-iron 
when  purchased  advise  that  the  attachment  piece  be  used  in 
turning  off  the  current.  The  reason  for  this  is  because  of  the 
flash  that  accompanies  the  bieak  in  the  circuit  when  disconnec- 
tion is  made  in  the  socket.  This-  flash  is  really  a  small  electric 
arc,  that  forms  as  the  circuit  is  broken  and  which  burns  away 
the  switch  at  the  point  of  disconnection.  The  arc  so  formed 


22_Electrfc  flat.iron  and 
its  attachments. 


328 


MECHANICS  OF  THE  HOUSEHOLD 


burns  away  the  contact  pieces  in  the  switch  and  it  is  soon  de- 
stroyed. The  attachment  piece  will  stand  this  wear  more  readily 
than  the  socket  switch  and  hence  is  preferable  for  disconnect- 
ing. The  irons  are  frequently  provided  with  a  special  switch 
for  the  service  required  in  the  flat-iron. 

A  spiral  spring  connected  to  the  attachment  cord  prevents 
it  from  kinking  when  in  use  and  thus  breaking  the  conducting 
wires.  The  attachment  cord  is  made  of  stranded  wires  to  make  it 
flexible.  The  strands  of  fine  copper  wire  are  made  to  correspond 


Large,  Comfortable,  Always 
Cool    Wood    Handle 


Electrically  Welded  Steel 
Handle  Supports,  no  Screws 
or  Rivets  to  Work  Loose 


\~  I  Perfectly  Balanced,  does 
\|  not  Tire  Arm    or  Wrist 


Beautiful  Nickel  Finish, 
Highly  Polished  Attractiv 
Prevents  Rust 


I  Cut    Away    Nose 
makes  Ironing  Easier 


Pressure  Plate,  Machine 
Milled,  Keeps  Heat  in 
Bottom  of  Iron 


Bolts  which  Clamp 
Pressure     Plate, 
Element  and  Bottom 
into  Practically 
One  Solid  Mass 


Indestructible,  Patented 
Sheathed    Heating 
Element,  Fool  Proof 


Extra  Large  Ironing 
Surface,  Smooth  as  Glass 


German  Silver,  Non-Corroding 
Bound,  Removable  Contacts 


i  Perfect  Heat  Distribution 
Over  Entire  Ironing  Surface 


Bottom  Plate,  Machine  Milled,  and 
Ground  Perfectly  Smooth  on  both  Sides 


FIG.  227. — Electric  flat-iron  showing  position  of  the  heating  element  and  contact 

plugs. 

to  the  gage  numbers  by  which  the  various  sizes  of  wire  are  des- 
ignated. In  use  the  constant  movement  of  the  iron  tends  to 
kink  the  cord  and  thus  breaks  the  strands.  This  action  is  most 
pronounced  at  the  point  where  the  cord  attaches  to  the  iron. 
For  this  reason  a  spiral  spring  wire  encloses  the  cord  for  a  short 
distance  above  the  attachment  piece.  After  long  usage  the  cord 
is  apt  to  break  in  this  vicinity.  It  may  usually  be  repaired  by 
cutting  off  the  ends  of  the  cords  and  new  connections  made  in 
the  attachment  piece.  When  the  iron  is  in  use  the  slack  por- 
tion of  the  cord  is  kept  from  interfering  with  the  work  by  the 


ELECTRICITY 


329 


coiled  wire  S,  which  connects  with  the  cord  at  any  convenient 
place. 

Electric  flat-irons  are  made  in  a  variety  of  styles  and  forms, 
the  mechanism  of  each  possessing  some  particular  advantage,  but 
all  are  provided  with  the  same  essential  parts,  chief  of  which 
is  the  heater  with  its  electric  attachment  piece.  In  Fig.  228 
is  shown  very  clearly  the  construction  of  an  example  in  which 
attention  is  called  to  the  points  of  excellence  that  are  required 
in  a  particularly  serviceable  iron.  The  form  of  the  heating  ele- 
ment which  is  recognized  in  the  iron  is  also  shown  in  Fig.  288. 

In  the  figure  the  heater  is  made  of  coils  of  resistance  wire, 
wound  on  a  suitable  frame  of  mica.  The  heating  element  is  in- 
sulated from  the  body  of  the  iron  with  sheets  of  mica,  this  being 
a  material  that  makes  an  excellent  insulator  and  is  not  materi- 


Heater  Coils 

Mica  Insulation 

FIG.   228. — Electric  flat-iron  heating  element. 

ally  affected  by  the  heat  to  which  it  is  subjected.  The  resist- 
ance wire  of  which  the  element  is  composed  is  especially  prepared 
to  resist  the  corroding  action  common  to  metal  when  heated  in  air. 
The  form  of  the  element  is  such  as  to  permit  the  least  movement 
of  the  turns  of  wire — in  their  constant  heating  and  cooling — that 
will  allow  the  different  spires  to  make  contact  and  thus  change 
the  resistance.  Should  the  spires  of  wire  come  together,  the 
current  would  be  shunted  across  the  contact  and  the  resistance 
of  the  element  decreased.  The  effect  of  such  a  reduction  of  re- 
sistance would  be  an  increased  flow  of  current  and  a  correspond- 
ing increase  of  heat.  In  this,  as  in  the  electric  lamp  and  all  other 
electric  circuits,  the  current,  voltage  and  resistance  follow  the 
conditions  of  Ohm's  law. 


330  MECHANICS  OF  THE  HOUSEHOLD 

Different  sizes  of  irons  will,  of  course,  require  different  amounts 
of  current.  A  6-pound  iron,  such  as  is  commonly  used  for  house- 
hold work,  will  take  about  5  amperes  of  current  at  110  volts 
pressure.  The  amount  of  electricity  the  iron  is  intended  to 
consume  is  generally  stamped  on  the  nameplate  of  the  manu- 
facturer. This  is  specified  by  the  number  of  volts  and 
amperes  of  current  the  iron  is  rated  to  use.  As  an  example, 
the  iron  may  be  marked,  Volts  105-115,  Amperes  2-3.  This 
indicates  that  the  iron  is  intended  to  be  used  on  circuits  that 
carry  electric  pressure  varying  from  105  to  115  volts  and  that 
the  heater  will  use  from  2  to  3  amperes  of  current,  depending 
on  the  voltage. 

To  estimate  the  cost  of  operating  such  an  iron,  it  is  neces- 
sary to  determine  the  number  of  watts  of  electric  energy  consumed. 
The  number  of  watts  of  energy  developed  under  any  condition 
will  be  the  product  of  the  volts  times  the  amperes.  Suppose  that 
in  the  above  example  the  iron  was  used  on  a  circuit  of  110  volts. 
Under  this  condition  the  current  required  to  keep  the  iron  hot 
would  be  2.5  amperes.  The  product  of  these  two  qualities,  110 
X  2.5  is  275  watts.  If  the  cost  of  electricity  is  10  cents  per 
kilowatt-hour  (1000  watts)  the  cost  of  operating  the  iron  would 
be 

275     X  10  cents  =  2%  cents  an  hour. 
1000  ] 

Since  the  electric  iron  requires  a  much  larger  amount  of  cur- 
rent than  is  usually  required  for  ordinary  lighting,  the  circuit 
on  which  it  is  used  should  receive  more  than  passing  attention. 
The  wires  should  be  of  size  amply  large  to  carry  without  heating 
the  current  necessary  for  its  operation.  This  topic  will  be  dis- 
cussed later  but  it  is  well  here  to  call  attention  to  the  necessity 
for  a  circuit  suited  to  the  required  current.  If  an  iron  requir- 
ing 5  amperes  of  current  is  attached  to  a  circuit  that  is  intended  to 
carry  only  3  amperes  the  conducting  wires  will  be  overheated 
and  may  be  the  cause  of  serious  results. 

The  Electric  Toaster. — As  shown  in  Fig.  229  the  toaster  is 
made  of  a  series  of  heating  elements  mounted  on  mica  frames  and 
supported  on  a  porcelain  base.  It  is  an  example  of  heating  by 
exposed  wires  and  direct  radiation.  The  heaters  H  are  coils  of 


ELECTRICITY 


331 


flat  resistance  wire  that  are  wound  on  wedge-shaped  pieces  of 
mica.  They  are  supported  on  a  wire  frame  that  is  formed  to  re- 
ceive slices  of  bread  on  each  side  of  the  heaters.  The  attach- 
ment piece  A  and  the  material  of  the  heater  is  similar  in  con- 
struction to  that  of  the  flat-iron.  The  electric  circuit  may  be 
traced  from  the  contacts  at  A  and  B  in  the  attachment  plug  by 
the  dotted  lines  which  indicate  the  wires  in  the  porcelain  base. 
The  current  traverses  each  coil  in  turn  and  connects  with  the 
next,  alternately  at  the  top  and  bottom.  The  resistance  is  such 
as  will  permit  the  voltage  of  the  circuit  to  send  through  the  coils 


FIG.  229. — The  electric  toaster. 

current  sufficient  to  raise  the  heaters  to  a  red  heat.  The  added 
resistance  of  the  hot  wires  decreases  the  flow  of  current  to  keep 
the  temperature  at  the  desired  degree. 

In  a  heater  of  this  kind  the  resistance  of  the  wire  may  in- 
crease with  age  and  the  coils  fail  to  glow  with  a  sufficient  bright- 
ness. The  reason  for  the  lack  of  heat  is  that  of  decrease  in  current, 
due  to  the  increased  resistance  of  the  wires.  This  condition  may 
be  corrected  by  the  removal  of  a  little  of  the  heater  coils.  If  a 
turn  or  two  of  the  heater  wire  is  removed,  the  resistance  of  the 
circuit  is  reduced  and  the  effect  of  the  increased  current  will 
produce  a  higher  temperature  in  the  heater. 


332  MECHANICS  OF  THE  HOUSEHOLD 

Motors. — As  a  means  of  developing  mechanical  power  in  small 
units,  the  electric  motor  has  made  possible  its  application  in 
many  household  uses  that  were  formerly  performed  entirely  by 
manual  labor.  As  a  domestic  utility  electrical  power  is  generated 
at  a  cost  that  is  the  least  expensive  of  all  its  applications. 
As  a  means  of  lighting  and  heating  electricity  has  had  to  compete 
with  established  methods  and  has  won  place  because  of  the  advan- 
tages it  possesses  over  that  of  cost.  In  the  development  of 
domestic  power  it  has  practically  no  opponent.  There  is  no  other 
form  of  power  that  can  be  so  successfully  utilized  in  delivering 
mechanical  work  for  the  purposes  required.  A  kilowatt  of 
electric  energy,  for  which  10  cents  is  a  common  price,  will  furnish 
a  surprising  amount  of  manual  labor.  Theoretically,  746  watts 
is  equal  to  1  horsepower.  The  commercial  kilowatt  is  rated  at 
an  hour  of  time,  and  is,  therefore,  equal  theoretically  to  1J/3 
horsepower  for  one  hour.  While  motors  cannot  be  expected  to 
transform  all  of  this  energy  into  actual  work  without  loss,  even 
at  the  low  rate  of  efficiency  attained  by  the  small  electric  mo- 
tor, they  furnish  power  at  a  relatively  small  cost. 

The  first  applications  of  electric  power  were  those  for  sewing 
machines,  fans,  washing  machines,  etc.  Its  use  has  made  pos- 
sible the  vacuum  cleaner,  automatic  pumping,  refrigeration, 
ventilation,  and  many  other  minor  uses  as  the  turning  of  ice- 
cream freezers,  churning  and  rocking  the  cradle. 

Electric  motors  are  made  in  many  sizes  for  power  generation 
and  in  forms  to  suit  any  application.  They  are  made  to  develop 
3/30  horsepower  and  in  other  fractional  sizes  for  both  direct 
and  alternating  current. 

In  applying  mechanical  power  to  any  particular  purpose 
special  appliances  must  be  made  to  adopt  electric  motors  to  the 
required  work.  This  is  accomplished  in  all  household  require- 
ments. The  motors  are  made  to  run  at  a  high  rate  of  speed  and 
must  be  reduced  in  motion  by  pulleys  or  gears  to  suit  their  con- 
dition of  operation.  As  in  the  case  of  electric  lamps  they  must 
be  suited  to  the  voltage  and  type  of  current  of  the  circuit  on 
which  they  are  to  be  used. 

Commercial  electric  circuits  furnish  electricity  in  two  types, 
direct  current,  ordinarily  termed  D.C.,  and  A.C.  or  alternating 
current.  The  terms  direct  and  alternating  current  apply  to  the 


ELECTRICITY  333 

direction  of  the  electric  impulses  which  constitute  the  transmitted 
energy.  In  the  electric  dynamo,  the  generation  of  the  current 
is  due  to  impulses  that  are  induced  in  the  wires  of  the  dynamo 
armature  as  they  pass4hrough  a  magnetic  field  of  great  intensity. 
These  electric  impulses  are  directed  by  the  manner  in  which  the 
wires  cut  across  the  lines  of  force  which  make  up  the  magnetic  field. 
In  the  case  of  the  direct  current  the  impulses  are  always  in  the 
same  direction  through  the  circuit,  while  in  the  other  they  are  in- 
duced alternately  to  and  fro  and  so  produce  alternating  current. 

The  term  electric  current  is  used  only  for  convenience  of  ex- 
pressing a  directed  form  of  energy.  Since  nothing  really  passes 
through  the  wires  but  a  wave  of  energy,  the  effect  is  the  same 
whether  the  electric  impulses  are  in  the  same  or  in  opposite  di- 
rections. An  incandescent  lamp  will  work  equally  well  on  'an 
A.C.  or  a  D.C.  circuit  of  the  proper  voltage;  but  in  the  case  of  mo- 
tors the  form  of  corstruction  must  be  suited  to  the  kind  of  cur- 
rent. Both  A.C.  and  D.C.  commercial  circuits  are  in  common  use, 
the  units  of  measurement  are  the  same  for  each  but  in  ordering  a 
motor  it  is  necessary  to  state  the  type  of  current  and  the  voltage, 
in  order  that  the  dealer  may  supply  the  required  machine.  In 
the  case  of  an  alternating  motor  it  is  further  necessary  to  state 
the  number  of  cycles  of  changes  of  direction  made  per  second 
in  the  A.C.  circuit.  All  of  this  information  may  be  obtained  by 
inquiring  of  a  local  electrician  or  of  the  power  station  from  which 
the  current  is  obtained. 

There  is  still  another  item  of  information  necessary  to  be 
supplied  with  an  order  for  a  motor,  other  than  those  of  fractional 
horsepower.  With  motors  of  a  horsepower  or  more  it  is  necessary 
to  state  the  number  of  phases  included  in  the  circuit.  This 
information  to  be  complete  must  state  whether  the  motor  is 
to  operate  on  a  single-phase,  two-phase,  or  three-phase  circuit. 
These  terms  apply  to  a  condition  made  possible  in  A.C.  generation 
that  permits  one,  two,  or  three  complete  impulses  to  be  developed 
in  a  circuit  at  the  same  time.  These  phases  are  transmitted 
by  three  wires,  any  two  of  which  will  form  a  circuit  and  give  a 
supply  of  energy  at  the  same  voltage.  Either  one  phase  or  all 
may  be  used  at  the  same  time  and  for  this  reason  the  phase  of  an 
A.  C.  motor  should  be  given  in  an  order.  To  make  the  information 
complete  there  should  be  included  the  number  of  cycles  or  com- 


334  MECHANICS  OF  THE  HOUSEHOLD 

plete  electric  impulses  per  second  produced  in  the  circuit.  Sup- 
pose that  a  1-horsepower  motor  is  required  to  work  on  an  A.C. 
circuit  of  110  volts.  Inquiry  of  the  electric  company  reveals 
that  the  circuit  is  three-phase  at  60  cycles  per  second.  The 
dealer  on  receiving  this  information  will  be  able  to  send  a  motor 
to  suit  your  conditions.  Most  A.C.  motors  of  1  horsepower  or 
less  are  of  the  single-phase  variety.  In  the  case  of  D.C.  motors 
it  is  necessary  only  to  state  the  voltage  of  the  circuit  to  make 
the  required  information  complete. 

Fuse  Plugs. — Every  electric  circuit  is  liable  to  occurrences 
known  as  short-circuiting  or  "  shorting."  This  is  a  technical 
term  describing  a  condition  where,  by  accident  or  design,  the 
wires  of  a  circuit  are  in  any  way  connected  by  a  low-resistance 
conductor  or  by  coming  directly  into  contact  with  each  other. 
In  case  of  shorting,  the  resistance  is  practically  all  removed  and 
the  amount  of  current  which  flows  through  the  circuit  is  so  great 
as  to  produce  a  dangerous  amount  of  heat  in  the  wires.  If  the 
covering  of  a  lamp  cord  becomes  worn  so  as  to  permit  the  bare 
wire  of  the  two  strands  to  come  together,  a  "  short "  is  produced. 
Immediately,  the  reduced  resistance  permits  the  electric  pressure 
to  send  an  amount  of  current  through  the  wires,  greater  than  they 
are  intended  to  carry.  When  this  occurs  an  electric  arc  will 
form  at  the  point  of  contact  with  the  accompanying  flash  of 
vaporizing  metal  and  the  wire  will  finally  burn  off.  Fires 
started  from  this  cause  are  not  uncommon. 

To  guard  against  accidents  from  short-circuiting,  every  elec- 
tric circuit  should  be  provided  with  fuses  which,  in  cases  of  emerg- 
ency, are  intended  to  melt  and  thus  break  the  circuit.  Fuses 
are  made  of  lead-composition  or  aluminum  and  are  used  in  the 
form  of  wire  or  ribbon-like  strips,  of  sizes  that  will  carry  a  definite 
amount  of  current.  They  are  designated  by  their  carrying 
capacity  in  amperes.  As  an  example:  a  2-ampere  fuse  will 
carry  2  amperes  of  current  without  noticeable  heating,  but  at  a 
dangerous  overload  the  fuse  will  melt  and  the  circuit  be  broken. 
Should  a  short-circuit  be  formed  at  any  time,  the  rush  of  current 
through  the  fuse  will  cause  it  almost  immediately  to  melt,  and 
stop  the  flow  of  current.  They  are,  therefore,  the  safeguard  of 
the  circuit  against  undue  heating  of  the  conducting  wires. 

When  an  open  fuse  blows  (melts),  the  heat  generated  by  the 


ELECTRICITY 


335 


arc,  formed  at  the  breaking  circuit,  is  so  sudden  that  there  is 
frequently  an  explosive  effect  that  throws  the  melted  metal  in 
all  directions,  and  in  case  it  comes  into  contact  with  combustible 
material  a  fire  may  result.  To  do  away  with  this  danger,  fire 
insurance  companies  in  their  specifications  of  electric  fixtures 
state  what  forms  of  fuses  will  be  acceptable  in  the  'buildings  to  be 
insured.  These  specifications  are  known  as  the  Underwriters 
Rules  and  may  be  obtained  from  any  fire  insurance  company. 
The  fuses,  or  fuse  plug,  as  they  are  commonly  called,  generally 
occupy  a  place  in  a  cabinet  or  distributing  panel,  near  the  point 
where  the  lead  wires  enter  the  building.  The  cabinet  contains 
the  porcelain  cutouts  for  sending  the  current  through  the  different 
circuits;  the  fuse  plugs  form  a  part  of  the  cutouts,  one  fuse  to  each 
wire.  The  cabinet  contains  be- 
sides the  cutouts  a  double-poled 
switch  to  be  used  for  shutting 
off  the  current  from  the  build- 
ing when  desired. 

Cabinets  for  this  purpose  are 
made  in  standard  form  of  wood 
or  steel  to  suit  the  condition  of 
service.  These  cabinets  may  be 
obtained  from  any  dealers  in 

electrical  supplies  or  the  cabinet  may  be  made  a  part  of  the 
house  since  they  are  only  small  shallow  closets.  Fig.  230  rep- 
resents such  a  cabinet  as  is  used  in  the  average  dwelling.  It 
is  made  of  a  light  wooden  frame  set  between  the  studding  of  a 
partition  at  any  convenient  place.  The  bottom  of  the  cabinet 
is  made  sloping  to  prevent  its  being  used  as  a  place  of  storage 
for  articles  that  might  lead  to  trouble.  The  cabinet  is  sometimes 
lined  with  asbestos  paper  as  a  prevention  from  fire  but  this  is 
not  necessary  as  the  fuse  plugs  and  their  receptacles,  when  of 
approved  design,  are  sufficient  to  prevent  accident. 

The  main  wires  which  supply  the  house  with  electricity- 
marked  lead  wires— are  brought  into  the  cabinet  as  shown  in 
Fig.  231  and  attached  to  the  poles  of  the  switch  S.  In  passing 
through  the  switch  the  lead  wires  each  contain  a  mica-covered 
fuse  plug  F,  that  will  be  described  later.  The  current  at  any  time 
may  be  entirely  cut  off  from  the  house  by  pulling  the  handle  H, 


FIG.  230. — Electric  cabinets. 


336 


MECHANICS  OF  THE  HOUSEHOLD 


which  is  connected  by  an  insulating  bar  and  the  contacts  N  of 
the  switch.  When  the  handle  H  is  pulled  to  separate  the  contact 
pieces,  all  electric  connection  is  severed  at  that  point. 

The  wattmeter  for  measuring  the  current  is  placed  at  the 
points  marked  meter,  as  a  part  of  the  main  circuit.  The  main 
wires  in  the  cabinet  terminate  in  the  porcelain  cutouts,  from 
which  are  taken  off  the  various  circuits  of  'the  house.  In  the 
figure,  three  such  cutouts  are  shown  making  three  circuits  marked 


Lead  Wires 
FIG.  231. — Electric  panel  containing  cutout  blocks,  fuses  and  switch. 

1,  2,  and  3.  In  circuit  No.  1,  the  fuses  are  marked  F.  These 
wires'are  joined  to  the  main  wires  at  the  points  marked  C  and  C". 
The  number  of  circuits  the  house  will  contain  depends  on  the 
number  of  lights  and  the  manner  in  which  they  are  placed.  The 
circuits  are  intended  to  be  arranged  so  that  in  case  of  a  short, 
no  part  of  the  house  will  be  left  entirely  in  darkness. 

Fuses  for  general  use  are  made  in  two  different  types — the 
plug  type  and  the  cartridge  type — each  of  which  conforms  to  the 
rules  of  the  Underwriters  Association.  Those  most  commonly 


ELECTRICITY 


337 


used  for  house  wiring  are  the  plug  type  shown  in  Fig.  232  and 
indicated  in  the  figure  just  described.  These  plugs  are  made  of 
porcelain  and  provided  with  a  screw  base  which  permits  their  be- 
ing screwed  into  place  like  an  incandescent  lamp.  The  front  of 
the  plug  is  arranged  with  a  mica  window  which  allows  inspection 
to  be  made  in  case  of  a  short,  the  blown  fuse  indicating  the  cir- 
cuit in  which  the  trouble  is  located.  Another  style  of  the  same 
type  of  plug,  known  as  the  re-fusable  fuse  plug,  permits  the  fuse 
to  be  replaced  after  the  wire  has  been  destroyed  by  a  short. 

The  second  type  is  commonly  known  as  the  cartridge  fuse  plug 
from  its  general  appearance.     This  fuse  is  shown  in  Fig.  233. 


FIG.  232. — Mica  cov- 
ered fuse  plug. 


FIG.  233. — Cartridge  fuse. 


FIG.  234.— Plug  re- 
ceptacle for  cartridge 
fuse. 


The  fusable  wire  is  enclosed  in  a  composition  fiber  tube,  the 
ends  of  which  are  covered  by  brass  caps  which  afford  contact 
pieces  in  the  fuse  receptacle  and  to  which  are  fastened  the  ends 
of  the  fuse  wire.  These  fuses  are  very  generally  employed  in 
power  circuits  and  others  of  large  current  capacity.  The  small 
circle  in  the  center  of  the  label  is  the  indicator.  When  the  fuse 
burns  out,  a  black  spot  will  appear  in  the  circle.  It  is  sometimes 
desirable  to  use  the  cartridge  fuse  plug  in  receptacles  intended 
for  the-  mica-covered  type.  The  use  of  the  cartridge  fuses  under 
this  condition  is  effected  by  use  of  a  porcelain  receptacle  such  as 
is  shown  in  Fig.  234;  the  cartridge  fuse  is  simply  inserted  into  the 
receptacle  which  is  then  screwed  into  the  socket  in  place  of  the 
mica  fuse. 

In  order  to  avoid  any  possible  chance  of  overloading  the  wires 
of  a  circuit,  fuses  are  installed  which  are  suited  to  the  work  to  be 
performed.  Suppose  that  there  are  ten  40-watt  lamps  that  may 


22 


338  MECHANICS  OF  THE  HOUSEHOLD 

be  used  on  a  circuit,  each  lamp  of  which  requires  Y\\  ampere 
of  current. 

110  X  C  =  40  watts 

n       40         4 

\j  —         =    r  ampere  per  lamp. 


Ten  such  lamps  require  ten  times  %i  ampere  or  4%j  =3.7 
amperes  to  supply  the  lamps. 

A  fuse  that  will  carry  3.7  amperes  of  current  will  supply  the 
circuit  but  a  5-ampere  fuse  will  permit  an  increase  in  the  size 
of  the  lamp  and  will  fulfill  all  the  necessary  conditions.  If, 
however,  an  electric  heater  requiring  7  amperes  were  attached  to 
the  circuit,  the  fuse  being  intended  for  only  5  amperes  would  soon 
burn  out.  When  a  fuse  burns  out  it  must  be  replaced  either  with 
an  entirely  new  receptacle  or  the  fuse  wire  must  be  replaced. 

It  sometimes  happens  that  in  case  of  a  blown  fuse  there  is  no 
extra  part  at  hand  and  a  wire  of  much  greater  carrying  capacity 
is  used  in  its  place.  It  should  be  remembered  that  in  this  prac- 
tice of  "  coppering"  a  blown  fuse,  has  taken  away  the  protection 
against  short-circuiting  with  its  possibility  of  mischief. 

When  a  short  occurs,  the  cause  should  be  sought  for.  It 
cannot  be  located  and  on  being  replaced  a  second  fuse  blows,  the 
services  of  an  electrician  should  be  secured. 

Electric  Heaters.  —  All  electric  heating  devices  —  whether  in 
the  form  of  hot  plates,  ovens,  stoves  or  other  domestic  heating 
apparatus  —  possess  heating  elements  somewhat  similar  to  the  flat- 
iron  or  the  toaster.  The  construction  of  the  heating  element  will 
depend  on  the  use  for  which  the  heater  is  intended  and  the  tem- 
perature to  be  maintained.  Hot  plates  similar  to  that  of  Fig. 
235  are  made  singly  or  two  or  more  in  combination.  When  the 
heat  is  to  be  transmitted  directly  by  radiation  the  heating  coils 
are  open,  as  with  the  toaster.  Under  other  conditions  the  coils 
are  embedded  in  enamel  that  is  fused  to  a  metal  plate.  In 
elements  of  this  kind  the  heat  is  transmitted  to  the  plate  entirely 
by  conduction  from  which  it  is  utilized  in  any  manner  requiring 
a  heated  surface.  The  form  of  the  heating  element  will,  therefore, 
depend  on  the  application  of  the  heat,  whether  it  is  by  direct 
radiation  or  by  a  combination  of  radiation  and  conduction. 

Electric  ovens  are  constructed  to  utilize  electric  heat  in_an 
insulated  enclosure.  Heat  derived  from  electricity  is  more 


ELECTRICITY  339 

expensive  than  from  other  sources  but  when  used  in  insulated 
ovens  it  may  be  made  to  conveniently  perform  the  service  of  that 
derived  from  other  fuels.  In  electric  ovens  the  heaters  are 
attached  to  inside  walls.  As  in  other  heating  elements  they  are 
arranged  to  suit  the  conditions  for  which  the  oven  is  to  be  used. 
The  heaters  are  usually  so  divided  as  to  permit  either  all  of  the 
heaters  to  be  used  at  the  same  time  to  quickly  produce  a  high 
temperature,  or  only  a  portion  of  the  heat  to  be  used  in  keeping 
up  the  temperature  lost  by  radiation.  Ovens  of  this  kind  may  be 
provided  with  regulators  by  means  of  which  the  heat  may  be 
automatically  kept  at  any  desired  temperature.  Such  heating 
and  temperature  regulation  may  be  used  to  produce  any  desired 
condition,  but  in  practice  the  cost  of  the  heat  is  the  factor  which 
determines  its  use.  Unless  electric  heat  is  conserved  by  insula- 
tion it  cannot  become  a  competitor  with  other  forms  of  heating. 


FIG.  235. — Electric  three-burner  hot  plate.     Electric  hot  plate. 

Electric  cooking  stoves  and  ranges  are  made  for  every  form  of 
domestic  and  culinary  service.  They  fulfill  many  purposes  that 
may  be  obtained  in  no  other  way.  As  conveniences,  the  cost  of 
heat  becomes  of  secondary  consideration  and  their  use  is  con- 
stantly increasing.  In  Fig.  236  is  an  example  of  a  time-controlled 
and  automatically  regulated  electric  range.  In  the  picture  is 
shown  separately  all  of  the  heaters  for  the  ovens  and  stove  top. 
The  part  S  shows  the  switches  attached  to  the  heaters  of 
the  stove  top,  which  is  raised  to  show  the  connecting  wires.  In 
the  larger  oven  there  are  two  heaters  of  1000  watts  each,  and  in 
the  smaller  oven  one  heater  of  850  watts.  Each  heater  may  be 
controlled  separately  with  a  switch  giving  three  regulations  of 
heat — high,  medium  and  low.  The  advantage  of  this  arrange- 
ment lies  in  the  fact  that  one  can  set  the  two  heaters  in  the  oven 
at  different  temperatures  which  will  permit  either  a  slow  or  quick 


340  MECHANICS  OF  THE  HOUSEHOLD 

heat,  but  when  the  predetermined  temperature  is  reached  the 
current  will  be  automatically  cut  off  by  the  circuit-breakers. 
Such  flexibility  of  heat  control  in  the  ovens  permits  the  operator 
to  apply  heat  at  both  top  and  bottom  for  baking  and  roasting 
at  just  the  desired  temperature.  This  arrangement  also  avoids 
the  danger  of  scorching  food  from  concentration  of  heat,  and 
warping  utensils  or  the  linings  of  the  oven.  All  oven  heaters  on 


FIG.  236. — Electric  range.     Showing  how  all  parts  can  be  removed  for  cleaning 

and  replacement. 

the  automatic  ranges  are  further  controlled  and  mastered  by  the 
circuit-breakers. 

Intercommunicating  Telephones. — This  form  of  telephone  is 
used  over  short  distances  such  as  from  room  to  room  in  buildings 
or  for  connecting  the.  house  with  the  stable,  garage,  etc.  It  is 
complete,  in  that  it  possesses  the  same  features  as  any  other 
telephone  but  the  signal  is  an  electric  call-bell  instead  of  the 
polarized  electric  bell  used  in  commercial  telephone  service. 


ELECTRICITY  341 

Any  telephone  is  made  to  perform  two  functions:  (1)  that  of 
a  signal  with  which  to  call  attention;  and  (2)  the  apparatus 
required  to  transmit  spoken  words.  In  the  intercommunicating 
telephone  or  interphone,  the  signal  is  made  like  any  call-bell  and 
parts  are  similar  to  those  described  under  electric  signals.  The 
bell-ringing  mechanism  is  included  in  the  box  with  the  trans- 
mitting apparatus  and  the  signal  is  made  by  pressing  a  push 
button.  It  is  not  suitable  for  connecting  with  public  telephones. 
Telephone  companies,  as  a  rule,  do  not  permit  connection  with 
their  lines  any  apparatus  which  they  do  not  control. 

The  interphone  of  Fig.  237  shows  the  instrument  complete 
except  the  battery.  This  form  of  instrument  is  inexpensive, 
easy  to  put  in,  simple  to  operate  and  sup- 
plies a  most  excellent  means  of  intercom- 
munication. Complete  directions  for  in- 
stallation are  supplied  with  the  phones  by 
the  manufacturers. 

Electric  Signals. — Electrical  signaling  de- 
vices for  household  use,  in  the  form  of  bells 
and  buzzers,  are  made  in  a  great  variety  of 
forms  and  sizes  to  suit  every  condition  of 
requirement.  The  vibrating  mechanism  of  FlG-  237.— The  m- 

,     ,  ,      tercommumcatmg 

the  doorbell  is  used  in  all  other  household     telephone, 
signals   except   that   of   the   magneto   tele- 
phone.    It   is   an  application    of  the  electromagnet,  in  which 
the  magnetism  is  applied  to  vibrate  a  tapper  against  the  rim 
of  a  bell. 

A  bell  system  consists  of  the  gong  with  its  mechanism  for 
vibrating  the  armature,  an  electric  battery  or  A.C.  transformer 
connected  to  the  magnet  coils  to  form  an  electric  circuit  and  a 
push  button  which  serves  to  close  the  circuit  whenever  the 
bell  is  to  be  sounded.  The  bell  system  is  an  open-circuit  form 
of  apparatus;  that  is,  the  circuit  is  not  complete  except  during 
the  time  the  bell  is  ringing.  By  pressing  the  push  button  the 
circuit  is  closed  and  the  electric  current  from  the  battery  flows 
through  the  magnet  and  causes  the  tapper  to  vibrate.  When  the 
push  button  is  released  the  circuit  is  broken  and  the  circuit 
stands  open  until  the  bell  is  to  be  again  used.  The  parts  of  the 
bell  mechanism  are  shown  in  Fig.  238  where  with  the  battery, 


342 


MECHANICS  OF  THE  HOUSEHOLD 


the  push  button  and  the  connecting  wires  is  shown  a  complete 
doorbell  outfit.  These  parts  may  be  placed  in  different  parts  of 
the  building  and  connected  by  wires  as  shown  in  the  Fig.  239. 
The  bell  is  located  at  R,  in  the  kitchen.  The  battery  is  placed 
in  the  closet  at  B,  the  connecting  wires  are  indicated  by  the  heavy 
lines;  they  are  secured  to  any  convenient  part  of  the  wall  and 
extend  into  the  basement  and  are  fastened  to  the  joists.  The 
wires  terminate  in  the  push  button  P,  where  they  pass  through 
the  frame  of  the  front  door.  The  wires  are  secured  by  staples 
to  keep  them  in  place.  Each  wire  is  fastened  separately  to  avoid 
the  danger  of  short-circuiting.  If  both  wires  are  secured  with  a 
single  staple  there  is  a  possibility  of  the  insulation  being  cut  and  a 
short  produced  across  the  staple. 

The  battery  B,  in  Fig.  238,  is  a  single  dry  cell  but  more  com- 
monly it  is  composed  of  two  dry  cells  joined  in  series.     It  is  con- 


FIG.  238. — Diagram  showing  the  parts  of  an  electric  doorbell. 

nected,  as  shown  in  the  figure,  to  the  binding  posts  PI  and  P%  of 
the  vibrating  mechanism,  the  push  button  PB  serving  to  make 
contact  when  the  circuit  is  to  be  closed.  When  the  button  is 
pressed  the  circuit  is  complete  from  the  +  pole  of  the  battery 
cell  through  the  binding  post  Pj,  across  the  contact  Ft  through 
the  spring  A,  through  the  magnet  coils  M,  across  the  binding 
post  P2  and  push  button  to  the  —  pole  of  the  cell.  The  vibration 
of  the  tapper  is  caused  by  the  magnetized  cores  of  the  coils  M. 
When  the  electric  current  flows  through  the  coils  of  wire,  the  iron 
cores  become  temporary  magnets.  This  magnetism  attracts 
the  iron  armature  attached  to  the  spring  A,  and  it  is  suddenly 
pulled  forward  with  energy  sufficient  to  cause  the  tapper  to  strike 
the  gong.  As  the  armature  moves  forward,  the  spring  contact 
at  F  is  broken  and  the  current  stops  flowing  through  the  magnet 


ELECTRICITY 


343 


coils.  When  the  current  ceases  to  flow  in  the  magnet  coils,  the 
cores  are  demagnetized  and  the  armature  is  drawn  back  by  the 
spring  A  to  the  original  position.  As  soon  as  the  contact  is 
restored  at  F  a  new  impulse  is  received  only  to  be  broken  as 
before.  In  this  manner  the  bell  continues  ringing  so  long  as  the 
push  button  makes  contact.  The  screw  at  F  is  adjusted  to  suit 
the  contact  with  the  spring  attached  to  the  armature.  The 
motion  of  the  armature  may  be  regulated  to  [a  considerable 


FIG.  239. — Example  of  an  electric  doorbell  installation. 

degree  by  this  adjustment.  When  properly  set  the  screw  is 
locked  in  place  by  a  nut  and  should  require  no  further 
attention. 

Electric  bells  vary  in  price  according  to  design  and  work- 
manship. A  bell  outfit  may  be  purchased  complete  for  $1  but 
it  is  advisable  to  install  a  bell  of  better  construction,  as  few  pieces 
of  household  mechanism  repay  their  cost  in  service  so  often  as  a 
well-made  bell.  The  bell  should  be  rigid,  well-constructed,  and 
the  contact  peice  F  should  be  adjustable.  This  part  F,  being 


344 


MECHANICS  OF  THE  HOUSEHOLD 


the  most  important  of  the  moving  parts  of  the  bell,  is  shown  sepa- 
rately in  Fig.  240.  Only  the  ends  of  the  magnet  coils  with  their 
cores  are  shown  in  the  figure.  The  contact  is  made  at  A,  by  the 
pressure  of  the  spring  against  the  end  of  the  adjustable  screw  D. 
When  the  screw  is  properly  adjusted  it  is  locked  securely  in  place 
by  the  nut  G.  The  screw  D  is  held  with  a  screw-driver  and  the 
nut  G  forced  into  position  to  prevent  any  movement.  If  the 
screw  is  moved,  so  that  contact  is  lost  at  A,  the  bell  will  not  ring. 
In  the  better  class  of  bells  the  point  of  the  screw  and  its  contact 

at  A  are  made  of  platinum 
to  insure  long  life.  With 
each  movement  of  the 
armature  a  spark  forms  at 
the  contact  which  wears 
away  the  point,  so  that  to 
insure  good  service  these 
points  must  be  made  of 
refractory  material. 

Buzzers. — Electric  bells 
are  often  objectionable  as 
signal  calls  because  of  their 
clamor,  but  with  the  re- 
moval of  the  bell  the  vi- 
brating armature  serves 
equally  well  as  a  signal  but 
without  the  undesirable 


JJJ  Magnet 


FIG.  240. — Diagram  of  the  vibrating  mech- 
anism used  in  buzzers  and  doorbells. 


noise.  With  the  bell  and 
tapper  removed  the  operat- 
ing mechanism  of  such  a  device  works  with  a  sound  that  has 
given  to  them  the  name  of  buzzers.  Fig.  241  illustrates  the 
form  of  an  iron-cased  buzzer  for  ordinary  duty.  The  working 
parts  are  enclosed  by  a  stamped  steel  cover  that  may  be  easily 
removed.  The  mechanism  is  quite  similar  to  that  already  de- 
scribed in  the  doorbell  and  Fig.  240  shows  in  detail  the  work- 
ing, parts.  The  noise,  from  which  the  device  takes  its  name,  is 
produced  by  the  armature  and  spring  in  making  and  breaking 
contact. 

Burglar  Alarms. — A  burglar  alarm  is  any  device  that  will 
give  notice  of  the  attempted  entrance  of  an  intruder.     It  is 


ELECTRICITY 


345 


usually  in  the  form  of  a  bell  or  buzzer  placed  in  circuit  with  a 
battery,  as  a  doorbell  system,  in  which  the  contact  piece  is 
placed  to  detect  the  opening  of  a  door  or  window.  The  contact 
is  arranged  to  start  the  alarm  whenever  the  window  or  door  is 
opened  beyond  a  certain  point.  The  attachment  shown  in  Fig. 
242  is  intended  to  form  the  contact  for  a  window.  It  is  set  in  the 
window  frame  so  that  the  lug  C  will  be  depressed  and  close  the 
alarm  circuit  in  case  the  sash  is  raised  sufficiently  to  admit  a  man. 
Each  window  may  be  furnished  with  a  similar  device  and  the 
doors  provided  with  suitable  contacts  which  together  form  a 
system  to  operate  in  a  single  alarm.  During  the  time  when  the 
alarm  is  not  needed  it  is  disconnected  by  a  switch.  The  windows 


FIG.24I 


FIG  .24-5 


FIG.242 

FIG.  241. — The  electric  buzzer. 
FIG.  242. — Contact  for  a  window  burgler  alarm. 
FIG.  243. — Trip  contact  which  announces  the  opening  of  a  door. 
FIG.  244.- — Contact  for  a  door  alarm. 
FIG.  245. — Doorway  or  hall  matting  with  contacts  for  electric  alarm. 

and  doors  are  sometimes  connected  with  an  annunciator  which 
will  indicate  the  place  from  which  an  alarm  is  given.  An  annun- 
ciator used  for  this  purpose  designates  the  exact  point  at  which 
the  contact  is  made  and  removes  the  necessity  of  searching  for 
the  place  of  attempted  entrance. 

In  Fig.  243  is  illustrated  one  form  of  door  trip  which  may  be 
used  on  a  door  to  announce  its  opening.  This  trip  makes  elec- 
tric connection  in  the  alarm  circuit  when  the  opening  door  comes 
into  contact  with  the  swinging  piece  T,  but  no  contact  is  made  as 
the  door  closes.  The  trip  is  fastened  with  screws  at  D  to  the 
frame  above  the  door.  The  opening  door  comes  into  contact  with 
T  and  moves  it  forward  until  the  electric  circuit  is  formed  at  C; 
after  the  door  has  passed,  a  spring  returns  it  to  place.  As  the 


346  MECHANICS  OF  THE  HOUSEHOLD 

door  is  closed,  the  part  T  is  moved  aside  without  making  elec- 
tric contact. 

Fig.  244  is  another  form  of  door  alarm  that  makes  contact  when 
the  door  is  opened  and  remains  in  contact  until  the  door  is  closed. 
The  part  P  is  set  into  the  door  frame  of  the  door  in  such  position 
that  the  contact  at  C  is  held  open  when  the  door  is  closed. 
When  the  door  is  opened  a  spring  in  C  closes  the  contact  and 
causes  the  alarm  to  sound.  It  continues  to  sound  until  the  door 
is  closed  and  the  contact  is  broken.  When  the  use  of  the  alarm 
is  not  required,  the  contact-maker  is  turned  to  one  side  and  the 
contact  is  held  open  by  a  catch.  It  is  put  out  of  use  by  pressing 
the  plunger  to  one  side. 

The  matting  shown  in  Fig.  245  is  provided  with  spring  contacts 
so  placed  that  no  part  may  be  stepped  upon  without  sounding 
the  alarm.  When  placed  in  a  doorway  and  properly  connected 
with  a  signal,  no  person  can  enter  without  starting  an  alarm.  The 
matting  is  attached  to  the  alarm  by  the  wires  C  and  contacts 
are  set  at  close  intervals  so  that  a  footstep  on  the  mat  must 
close  at  least  one  contact. 

Annunciators. — It  is  often  convenient  for  a  bell  or  buzzer  to 
serve  two  or  more  push  buttons  placed  in  different  parts  of  the 
house.  In  order  that  there  may  be  means  of  designating  the 
push  button  used — when  the  bell  is  rung — an  annunciator  is  pro- 
vided. This  is  a  box  arranged  with  an  electric  bell  and  the 
required  number  of  pointers  and  fingers  corresponding  to  the 
push  buttons.  In  Fig.  246  is  shown  an  annunciator  with 
which  two  push  buttons  are  served  by  the  single  bell.  The 
annunciator  is  placed  at  the  most  convenient  place  of  observa- 
tion, usually  in  the  kitchen.  When  the  bell  rings  the  pointer 
indicates  the  push  button  that  has  last  been  used.  In  hotels  or 
apartment  houses  an  annunciator  with  a  single  bell  may  thus 
serve  any  number  of  push  buttons.  In  a  burglar-alarm  system 
the  annunciator  numbers  are  arranged  to  indicate  the  windows  and 
other  openings  at  which  entrance  might  be  made.  When  the 
alarm  sounds  the  annunciator  indicates  the  place  from  which  the 
alarm  is  made. 

Table  Pushes. — Call  bells  to  be  rung  from  the  dining-room 
table  are  connected  with  an  annunciator  or  to  a  separate  bell. 
The  table  pushes  may  be  temporarily  clamped  on  the  edge  of  the 


ELECTRICITY 


347 


table  and  connected  by  a  cord  to  an  attachment  set  in  the  floor 
or  the  connection  may  be  made  by  a  foot  plate  set  on  the  floor. 
In  Fig.  247  is  shown  a  form  of  push  P  which  is  intended  to  be 
clamped  to  the  edge  of  the  table  under  the  cloth.  The  plate  F 
forms  the  floor  connection.  It  is  set  permanently  with  the  up- 
per edge  flush  with  the  surface  of  the  floor.  The  part  S,  in  which 
the  connecting  cord  terminates,  when  inserted  in  the  floor  plate, 
makes  contact  at  the  points  C  to  form  an  electric  circuit  with 
the  battery.  The  foot  plate  shown  in  Fig.  248  is  only  an  enlarged 
push  button  which  is  set  under  the  table  in  convenient  positions 
to  be  pressed  with  the  foot.  Its  connection  might  be  made  as 


FIG.  246 


FIG.  249 

FIG.  246. — A  kitchen  annunciator. 

FIG.  247. — Plug  attachment  and  table  push  for  a  dining  table. 
FIG.  248. — Foot  plate  and  contact  for  table  bell. 
FIG.  249. — Call  bell  attachment  with  detachable  contact  piece. 

indicated  or  with  the  same  floor  connection  as  that  of  the  pre- 
ceding figure.  Fig.  249  is  a  simpler  form  of  floor  push  in  which  a 
metallic  plug  is  inserted  in  the  floor  place.  When  the  plug  R 
is  pressed,  contact  is  made  at  the  points  C  to  form  the  circuit 
with  the  battery  and  bell. 

Bell-ringing  Transformers.— The  general  employment  of  al- 
ternating electricity  for  all  commercial  service  requiring  dis- 
tant transmission  is  because  of  the  possibility  of  changing  the 
voltage  to  suit  any  condition.  The  energy  transmitted  is  de- 
termined by  the  amperes  of  current  carried  by  the  wires  and  the 


348  MECHANICS  OF  THE  HOUSEHOLD 

volts  of  pressure  by  which  it  is  impelled.     The  product  of  these 
two  factors  determines  the  watts  of  energy  transmitted. 

110  volts  X  1  ampere  =110  watts. 

If  the  voltage  is  raised  to  say  ten  times  the  original  intensity 
with  the  same  current,  the  quantity  of  energy  is  ten  times  the 

original  amount. 

i 

1100  volts  X  1  ampere  =  1100  watts. 

The  carrying  capacity  of  wires  is  determined  by  the  amperes 
of  current  that  can  be  transmitted  without  heating. 

The  cost  of  copper  wire  is  such  that  the  expense  of  large  wires 
for  carrying  a  large  current  is  unnecessary  where  by  raising  the 
voltage  a  small  wire  will  perform  the  same  service ;  therefore,  it  is 
desirable  to  transmit  electric  energy  at  a  high  voltage  and  then 
transform  it  to  suit  the  condition  of  usage. 

Alternating  current  may  be  transformed  to  a  higher  or  a  lower 
voltage  to  suit  any  condition  by  using  step-up  or  step-down 
transformers. 

A  transformer  is  a  simple  device  composed  of  two  coils  of  wire 
wound  on  a  closed  core  of  iron.  The  coil  into  which  is  sent  the 
inducing  current  is  the  primary.  That  in  which  the  current  is 
induced  is  the  secondary  coil.  The  change  in  voltage  between 
primary  and  secondary  coils  vary  as  the  number  of  turns  of  wire 
which  compose  the  coils.  The  house  circuit  may  be  stepped 
down  from  the  customary  110  volts  to  a  voltage  such  as  is  fur- 
nished by  a  single  dry  cell,  or  a  battery  of  cells. 

In  principle,  the  action  of  the  transformer  is  the  same  as  that 
of  the  induction  coil,  a  detailed  explanation  of  which  will  be  found 
in  any  text-book  of  physics.  Each  impulse  of  current  in  the 
primary  coil  of  the  transformer  magnetizes  its  core  and  the  mag- 
netism thus  excited  induces  a  corresponding  current  in  the 
secondary  coil.  Since  alternating  current  in  the  primary  coil 
constantly  changes  the  polarity  of  the  core,  each  change  of  mag- 
netism induces  current  in  the  secondary  coil. 

Small  transformers  are  frequently  used  for  operating  doorbells, 
annunciators,  etc.,  in  place  of  primary  batteries.  These  trans- 
formers are  also  used  to  supply  current  for  lighting  low-power 
tungsten  lamps  that  cannot  be  used  with  the  ordinary  voltages 


ELECTRICITY 


349 


employed  in  house  lighting.  The  primary  wires  of  the  trans- 
former are  attached  to  the  service  wires  in  the  house  and  from 
the  secondary  wires  voltages  are  taken  to  suit  the  desired  purposes. 
Fig.  250  shows  such  a  transformer  with  the  cover  partly 
broken  away  to  expose  the  interior  construction.  The  wires 
from  house  mains  MM  lead  the  current  to  the  primary  coil  P 
which  is  a  large  number  of  turns  of  fine  wire  wound  about  a  soft- 
iron  core.  The  induced  current  in  the  secondary  coil  S  is  taken 
from  the  contact  points  1,  2,  3  and  4.  The  construction  of  the 
transformer  coils  shown  in  Fig.  250  indicates  the  primary  wires 
at  LL  of  Fig.  251.  The  wires  of  the  primary  coil  are  permanently 
attached  to  house  wires.  The  reactive  effect  of  the  magnetism 


FIG.  250. — Doorbell  trans- 
former. 


FIG.  251. — Details  of  doorbell 
transformer. 


in  the  coil  permits  Only  enough  current  to  flow  as  will  keep  the 
core  excited.  This  is  a  step-down  transformer  and  the  secondary 
coil  contains  fewer  turns  of  wire  than  the  primary  coil.  Since 
the  voltage  induced  in  the  secondary  coil  is  determined  by  the 
number  of  turns  of  wire  in  action,  this  coil  is  so  arranged  that 
circuits  formed  by  attachment  with  different  contacts  give  a 
variety  of  voltages.  The  numbers  on  the  front  of  Fig.  250 
correspond  to  those  of  Fig.  251.  The  coils  between  contact  1 
and  the  others  2,  3  and  4,  represent  different  number  of  turns  of 
wire  and  in  them  is  induced  voltages  corresponding  with  the 
number  of  turns  of  wire  in  each. 


350  MECHANICS  OF  THE  HOUSEHOLD 

The  Recording  Wattmeter. — To  determine  the  amount  of  elec- 
tricity used  by  consumers,  each  circuit  is  provided  with  some  form 
of  wattmeter.  These  meters  might  be  more  correctly  called 
watt-hour  meters  since  they  register  the  watt-hours  of  electrical 
energy  that  pass  through  the  circuit. 

In  the  common  type  of  meter,  the  recording  apparatus  in  com- 
posed of  a  motor  and  a  registering  dial.  The  motor  is  intended 
to  rotate  at  a  rate  that  is  proportional  to  the  amount  of  pass- 
ing current.  An  example  of  this  device  is  the  Thompson  induc- 
tion meter  of  Fig.  252.  The  motion  of  the  aluminum  disc  seen 
through  the  window  in  front  indicates  at  any  time  the  rate  at 
which  electricity  is  being  used.  This  constitutes  the  rotating 
part  of  the  motor.  It  is  propelled  by  the  magnetism,  created  by 
the  passing  current,  and  is  sensitive  to  every 
change  that  takes  place  in  the  electric  circuit. 
Each  lamp,  heater  or  motor  that  is  brought 
into  use  or  turned  off  produces  a  change  of 
current  in  the  conducting  wires  and  this  change 
is  indicated  by  the  rate  of  rotation  of  the  disc. 
FIG.  252.  Record-  Each  rotation  of  the  disc  represents  the  pas- 

ing  watt  meter.  •   *»    • ,  r     i      ,    •   • ,       ,  i     .    • 

sage  of  a  definite  amount  of  electricity  that  is 
recorded  on  the  registering  dials. 

The  shaft  on  which  the  disc  is  mounted  is  connected  with  the 
recording  mechanism  by  a  screw  which  engages  with  the  first  of  a 
train  of  gears.  These  gears  have,  to  each  other,  a  ratio  of  10 
to  1;  that  is,  ten  rotations  of  any  right-hand  gear,  causes  one 
rotation  of  the  gear  next  to  the  left.  The  pointers  on  the  dial 
are  attached  to  the  gear  spindles.  One  rotation  of  the  right- 
hand  dial  will  move  the  pointer  next  to  the  left  one  division 
on  its  dial.  Each  dial  in  succession  will  move  in  like  ratio. 

The  meters  are  carefully  calibrated  and  usually  record  with 
truthfulness  the  amount  of  electricity  used.  They  are,  however, 
subject  to  derangement  that  produces  incorrect  registration. 

To  Read  the  Meter. — First,  note  carefully  the  unit  in  which 
the  dial  of  the  meter  reads.  The  figures  above  the  dial  circle 
indicate  the  value  of  one  complete  revolution  of  the  pointer  in 
that  circle.  Therefore,  each  division  indicates  one-tenth  of  the 
amount  marked  above  or  below  the  circle. 

Second,  in  reading,  note  the  direction  of  rotation  of  the  pointers. 


ELECTRICITY  351 

Commencing  at  the  right,  the  first  pointer  rotates  in  the  direction 
of  the  hands  of  a  clock  (clockwise) ;  the  second  rotates  counter- 
clockwise; the  third,  clockwise;  etc.,  alternately.  The  direction 
of  rotation  of  any  one  pointer  may  easily  be  determined  by 
noting  the  direction  of  the  sequence  of  figures  placed  around 
each  division.  The  arrows  (shown  above)  indicate  the  direction 
of  rotation  of  the  pointers  when  the  meter  is  in  operation. 

Third,  read  the  figures  indicated  by  the  pointers  from  right 
to  left,  setting  down  the  figures  as  they  are  read,  i.e.,  in  a  position 
relative  to  the  position  of  the  pointers.  NOTE:  One  revolution  of 
the  first  or  right-hand  pointer  makes  one-tenth  of  a  revolution  of 
the  pointer  next  to  it  on  the  left.  One  revolution  of  this  second 
pointer  makes  one-tenth  of  a  revolution  of  the  pointer  next  to  it 
on  the  left,  etc.  Therefore,  if,  when  reading  the  dial,  it  is  found 
that  the  second  pointer  rests  very  nearly  over  one  of  the  tenth 
divisions  and  it  is  doubtful  as  to 
whether  it  has  passed  that  mark, 
it  is  only  necessary  to  refer  to  the 
pointer  next  to  it  on  the  right. 
If  this  pointer  on  the  right  has 
not  completed  its  revolution,  it 

,  FIG.  253a.— This  dial  reads  9484 

shows  that  the  second  pointer  has  kilowatt  hours. 

not  yet   reached  the  division  in 

question.     If  it  has  completed  its  revolution,  that  is,  passed  the 

zero,  it  indicates  that  the  second  pointer  has  reached  the  division 

and  the  figure  corresponding  is  to  be  set  down  for  the  reading. 

The  foregoing  also  applies  to  the  remaining  pointers.  When 
it  is  desired  to  know  whether  a  pointer  has  passed  a  tenth  di- 
vision mark,  it  is  necessary  to  refer  only  to  the  next  pointer 
to  the  right  of  it. 

Fourth,  see  if  the  register  is  direct-reading,  i.e.,  has  no  multi- 
plying constant.  Some  registers  are  not  direct-reading  in  that 
they  require  multiplying  the  dial  reading  by  a  constant  such 
as  10  or  100  in  order  to  obtain  the  true  reading.  If  the  register 
bears  some  notation  such  as  "  Multiply  by  100,"  the  reading 
as  indicated  by  the  pointers  should  be  multiplied  by  10  or  100 
as  the  case  may  be  to  determine  the  true  amount  of  energy 
consumed. 

Some  of  the  earlier  forms  of  meters  were  equipped  with  what 


KILOWATT    HOURS 


352 


MECHANICS  OF  THE  HOUSEHOLD 


is  known  as  a  "non-direct-reading  register."  In  this  case,  the 
reading  must  be  multiplied  by  the  figure  appearing  on  the  dial 
as  just  explained,  but  the  dial  differs  from  those  just  described 
in  that  the  multiplying  constant  is  generally  a  fraction  such  as 
J«2,  etc.,  and  the  dial  has  five  pointers.  This  older  style  of 
register  reads  in  "  watt-hours"  of  "  kilo  watt-hours." 

Fifth,  the  reading  of  the  dial  does  not  necessarily  show  the 
watt-hours  used  during  the  past  month.  In  other  words,  the 
pointers  do  not  always  start  from  zero.  To  determine  the  num- 
ber of  watt-hours  used  during  a  certain  period  it  is  necessary  to 
read  the  dial  at  the  begining  of  a  period  and  again  at  the  end 
of  that  period.  By  subtracting  the  first  reading  from  the  second, 
the  number  of  watt-hours  or  kilowatt-hours  used  during  the 
period  is  obtained. 

The  meter  man,  having  in  his  possession  a  record  of  the 
readings  of  each  customer's  meter  for  the  preceding  months,  is 
thus  able  to  determine  the  amount  of  energy  consumed  monthly. 


EXAMPLES  OF  METER  READINGS 

Fig.   253a  shows  an  example  of  an  ordinary   dial   reading. 
Commencing  at  the  first  right-hand   pointer,   Fig.   253c,   it  is 


KILOWATT  HOURS 


FIG.  253&.— -This  dial  reads  997 
kilowatt  hours. 


FIG.   253c. — This  dial  reads  9121 
kilowatt  hours. 


noted  that  the  last  figure  passed  over  by  the  pointer  is  1. 
The  next  circle  to  the  left  shows  the  figure  last  passed  to  be 
2, .  bearing  in  mind  that  the  direction  of  the  rotation  of  this 
pointer  is  counter-clockwise.  The  last  figure  passed  by  the  next 
pointer  to  the  left  is  1,  while  that  passed  by  the  last  pointer  to 
the  left  is  obviously  9.  The  reading  to  be  set  down,  therefore, 
is  9121. 

In   a    similar  manner  the  dial  shown  in  Fig.  2536  may  be 
read.     In  this  case,  however,  three  of  the  pointers  rest  nearly 


ELECTRICITY  353 

over  the  divisions  and  care  must  be  used  to  follow  the  direction 
to  avoid  error.  Commencing  at  the  right,  the  first  pointer  indi- 
cates 7.  The  second  pointer  has  passed  9  and  is  approaching  0. 
The  third  pointer  appears  to  rest  directly  over  0,  but  since  the 
second  pointer  reads  but  9,  the  third  cannot  have  completed  its 
revolution  and  hence  the  figure  last  passed  is  set  down  which 
in  this  case  is  9.  Similarly,  the  fourth  or  left-hand  pointer 
appears  to  rest  directly  over  1  but  by  referring  to  the  pointer 
next  to  it  on  the  right,  we  find  that  its  indication  is  9  as  just 
explained.  Therefore,  the  fourth  pointer  cannot  have  reached 
1,  and  so  the  figure  last  passed  which  is  0  is  set  down,  which  in 
this  case  is  9.  Similarly,  the  fourth  or  left-hand  pointer  appears 
to  rest  directly  over  1,  but  by  referring  to  the  pointer  next  to 
it  on  the  right  we  find  that  its  indication  is  9  as  just  explained. 
Therefore,  the  fourth  pointer  cannot  have  reached  1,  and  so 
we  set  down  the  figure  last  passed  which  is  0.  The  figures  as 
they  have  been  set  down,  therefore,  are  0997,  which  indicates 
that  997  kilowatt-hours  of  electricity  have  been  used. 

If,  for  example,  the  reading  of  this  meter  for  the  preceding 
month  was  976  kilowatt-hours,  the  number  of  kilowatt-hours 
used  during  that  month  would  be  997  —  976  =  21  kilowatt- 
hours. 

State  Regulation  of  Meter  Service. — Electric  wattmeters  are 
subject  to  errors  that  may  cause  them  to  run  either  fast  or  slow. 
Complaints  made  of  inaccurate  records  or  readings  are  usually 
rectified  by  the  electric  company.  In  many  States  all  public 
utilities  are  governed  by  laws  that  are  formulated  by  public 
utilities  commissions  or  other  bodies  from  which  may  be  obtained 
bulletins  fully  describing  the  conditions  required  of  public  service 
corporations  or  owners  of  public  utilities.  The  following  quota- 
tion from  Bulletin  No.  V.,  233  of  the  Railroad  Commission  of 
Wisconsin,  will  give  an  illustration  of  the  requirement  in  that 
State. 

RULE  14. — CREEPING  METERS. — No  electric  meter  which  registers  upon 
"no  load"  shall  be  placed  in  service  or  allowed  to  remain  in  service. 

This  means  that  when  no  electricity  is  being  used  in  the  sys- 
tem the  motor  disc  should  remain  stationary  and  if  it  shows  any 
motion  under  such  condition  it  is  not  recording  accurately. 

23 


354  MECHANICS  OF  THE  HOUSEHOLD 

PERIODIC  TESTS 

RULE  17. — Each  watt-hour  meter  shall  be  tested  according  to  the  fol- 
lowing schedule  and  adjusted  whenever  it  is  found  to  be  in  error  more  than 
1  per  cent.,  the  tests  both  before  and  after  adjustment  being  made  at 
approximately  three-quarters  and  one-tenth  of  the  rated  capacity  of  the 
meter.  Meters  operated  at  low  power-factor  shall  also  be  tested  at  ap- 
proximately the  minimum  power-factor  under  which  they  will  be  required 
to  operate.  The  tests  shall  be  made  by  comparing  the  meter,  while  con- 
nected in  its  permanent  position,  on  the  consumer's  premises  with  approved, 
suitable  standards,  making  at  least  two  test  runs  at  each  load,  of  at  least 
30  seconds  each,  which  agree  within  1  per  cent. 

Single-phase,  induction-type  meters  having  current  capacities  not  ex- 
ceeding 50  amperes  shall  be  tested  at  least  once  every  4  months  and  as  much 
oftener  as  the  results  obtained  shall  warrant. 

All  single-phase  induction-type  meters  having  current  capacities  exceed- 
ing 50  amperes  and  all  polyphase  and  commutator-type  meters  having  vol- 
tage ratings  not  exceeding  250  volts  and  current  capacities  not  exceeding 
50  amperes  shall  be  tested  at  least  once  every  12  months. 

All  other  watt-hour  meters  shall  be  tested  at  least  once  every  6  months. 

RULE  20. — REQUEST  TESTS. — Each  utility  furnishing  metered  electric 
service  shall  make  a  test  of  the  accuracy  of  any  electricity  meter  upon 
request  of  the  consumer,  provided  the  consumer  does  not  request  such 
test  more  frequently  than  once  in  6  months.  A  report  giving  the  results 
of  each  request  test  shall  be  made  to  the  consumer  and  the  complete, 
original  record  kept  on  file  in  the  office  of  the  utility. 

Electric  Batteries. — Electric  batteries  are  composed  of  elec- 
tric cells  that  are  made  in  two  general  types:  the  primary  cell, 
in  which  electricity  is  generated  by  the  decomposition  of  zinc; 
and  the  secondary  cell  or  storage  cell  in  which  electricity  from  a 
dynamo  may  be  accumulated  and  thus  stored.  Electric  cells  are 
the  elements  of  which  electric  batteries  are  made;  a  single  elec- 
tric cell  is  often  called  a  battery  but  the  battery  is  really  two 
or  more  cells  combined  to  produce  effects  that  cannot  be  attained 
by  a  single  element. 

Both  primary  and  secondary  batteries  form  a  part  of  the  house- 
hold equipment  but  the  work  of  the  secondary  battery  is  used 
more  particularly  for  electric  lighting,  the  operation  of  small 
motors  and  for  other  purposes  where  continuous  current  is  re- 
quired. It  will,  therefore,  be  considered  in  another  place. 

Primary  batteries  are  used  to  operate  call-bells,  table  pushes, 
buzzers,  night  latches  and  various  other  forms  of  electric  alarms 
besides  which  they  are  used  in  gas  lighters,  thermostat  motors 


ELECTRICITY 


355 


and  for  many  special  forms,  all  of  which  form  an  important  part 
in  the  affairs  of  everyday  life.  Primary  battery  cells  for  house- 
hold use  are  made  to  be  used  in  the  wet  and  dry  form,  but  the 
dry  cell  is  now  more  extensively  used  than  any  other  kind  and 
for  most  purposes  has  supplanted  the  wet  form. 

Formerly  all  primary  cells  were  made  of  zinc  and  copper  plates 
placed  in  a  solution  called  an  electrolite,  that  dissolved  the  zinc 
and  thus  generated  electricity,  the  electrolite  acting  as  a  con- 
ductor of  the  electricity  to  the  opposite  plate.  In  later  elec- 
tric cells  the  copper  was  replaced  by  plates  of  carbon  and  from 
the  zinc  and  carbon  cell  was  finally  evolved  the  present-day 


FIG.      254.— Elec- 
tric dry  cell. 


Carbon  and 

Salammoniac 

Paste 


FIG.  255. — Details  of  electric 
dry  cell. 


dry  cell.  When  the  use  of  electric  cells  reached  a  point  where 
portable  batteries  were  required,  a  form  was  demanded  from 
which  the  solution  could  not  be  lost  accidentally.  The  first 
electric  cells  in  which  the  electrolite  was  not  fluid  was,  therefore, 
called  a  dry  cell.  These  cells  are  not  completely  dry.  The 
electrolite  is  made  in  the  form  of  a  paste  that  acts  in  the  same 
manner  as  the  fluid  electrolite  and  is  only  dry  in  that  it  is  not  fluid. 
In  construction  the  dry  cell  is  shown  in  Figs.  254  and  255, 
the  former  showing  its  exterior  and  the  latter  exposing  its  in- 
ternal construction.  The  container  is  a  zinc  can  which  is  lined 
with  porous  paper  to  prevent  the  filler  from  coming  into  contact 
with  the  zinc.  The  zinc  further  is  the  active  electrode,  the 


356  MECHANICS  OF  THE  HOUSEHOLD 

chemical  destruction  of  which  generates  the  electricity.  The 
parts  enclosed  in  the  container  are:  a  carbon  rod,  which  acts 
as  the  positive  pole;  and  the  filler,  composed  of  finely  divided 
carbon  mixed  with  manganese  dioxide  and  wet  with  a  solution 
of  salammoniac.  The  composition  plug,  made  of  coal-tar  prod- 
ucts and  rosin,  is  intended  to  keep  the  contents  of  the  can  in 
place  and  prevent  the  evaporation  of  the  moisture.  Binding 
posts  attached  to  the  carbon  rod  and  soldered  to  the  can  furnish 
the  +  and  —  poles. 

In  the  action  of  cell,  the  salammoniac  attacks  the  zinc  in 
which  chemical  action  electricity  is  evolved.  The  electricity  is 
conducted  to  the  carbon  pole  through  the  carbon  and  the  salam- 
moniac solution  which  in  this  case  is  the  electrolite.  In  the 
dissolution  of  the  zinc,  hydrogen  gas  is  liberated  which  adds  to 
the  resistance  of  the  cell  and  thus  reduces  the  current.  The 
presence  of  the  hydrogen  is  increased  when  the  action  of  the  cell 
is  rapid  and  the  decrease  in  current  is  said  to  be  due  to  polari- 
zation. The  manganese  dioxide  is  mixed  with  the  filler  in  order 
that  the  free  hydrogen  may  combine  with  the  oxide  and  thus 
reduce  the  resistance.  This  process  is  known  as  depolarization. 
The  combination  between  the  hydrogen  and  the  oxide  is  slow 
and  for  this  reason  the  depolarization  of  batteries  sometimes 
require  severals  hours.  Dry  cells  are  usually  contained  in  paper 
cartons  to  prevent  the  surfaces  from  coming  into  contact  and 
thus  destroying  their  electrical  action. 

The  best  cell  is  that  which  gives  the  greatest  amount  of  cur- 
rent for  the  longest  time.  Under  any  condition  the  working 
value  of  a  cell  is  determined  by  the  number  of  amperes  of  current 
it  can  furnish.  The  current  is  measured  by  a  battery  tester 
such  as  Fig.  257.  The  +  connection  of  the  tester  is  placed  in 
contact  with  the  +  pole  of  the  cell  or  battery  and  the  other  con- 
nection placed  on  the  -  -  pole.  The  pointer  will  immediately 
indicate  the  current  given  out  by  the  battery.  A  new  dry  cell 
will  give  20  or  more  amperes  of  current  for  a  short  time  but  if 
used  continuously  the  quantity  of  current  will  be  reduced  by 
polarizing  until  but  a  very  small  amount  is  generated.  A  cell 
that  indicates  less  than  5  amperes  should  be  replaced.  If  short- 
circuited,  that  is  if  the  poles  are  connected  without  any  interven- 
ing resistance,  a  large  amount  of  current  will  be^given  but  the 


ELECTRICITY  357 

cell  will  soon  wear  out  and  possibly  be  ruined.  A  cell  should, 
therefore,  never  be  allowed  to  become  short-circuited.  The  vol- 
tage of  a  cell  is  practically  continuous  and  should  be  from  1.5 
to  1  volt.  It  is  quite  possible  that  a  cell  may  possess  its  normal 
voltage  and  yet  deliver  little  current;  the  voltage  of  a  cell  does 
not  indicate  its  working  property.  In  order  to  be  assured  of 
active  cells  they  should  be  tested  at  the  time  of  purchase  with 
an  ammeter. 

The  moisture  in  the  paste  of  a  cell  is  that  which  forms  the 
circuit  between  the  zinc  and  the  carbon  elements.  If  the  paste 
has  dried  out  its  resistance  is  increased  and  the  cell  generates 
little  current.  The  voltage  of  such  a  cell  may  be  normal  while 
the  amperage  is  very  low.  Cells  in  this  condition  may  be  revived 
by  adding  moisture  to  the  paste  as  a  temporary  remedy.  This 
may  be  accomplished  by  puncturing  the  can  with  a  nail  and  add- 
ing water.  A  solution  of  salammoniac  may  be  used  instead  of 
water  and  the  cell  soaked  to  accomplish  the  same  purpose;  this, 
however,  is  only  a  temporary  expedient. 

Temperature  influences  the  working  properties  of  an  electric 
cell  in  pronounced  manner.  The  moisture  contained  in  the  cell 
is  composed  of  ammonium  chloride  and  zinc  chloride  and  con- 
sequently the  resistance  of  the  cell  increases  with  the  fall  of  tem- 
perature ;  the  effect  of  the  resistance  thus  added  is  a  decrease  in 
the  flow  of  current.  Batteries  should  be  kept  in  a  temperature 
as  nearly  as  possible  that  of  70°F.  The  battery  regains  its 
normal  rate  of  discharge  when  the  temperature  is  restored. 

The  normal  voltage  and  amperage  for  a  given  make  of  cell  is 
practically  the  same  for  all.  The  size  of  the  cell  does  not  in 
any  way  influence  the  voltage.  Small  cells  and  large  cells  are 
the  same.  The  large  cells  are  advantageous  only  in  that  they 
give  out  a  greater  number  of  ampere-hours  of  energy.  All  bat- 
teries are  rated  in  the  number  of  ampere-hours  of  current  they 
are  capable  of  furnishing.  The  amper-hour  represents  an 
ampere  of  current  for  one  hour.  On  this  basis  all  batteries  are 
rated  for  the  total  amount  of  energy  they  are  capable  of  pro- 
ducing. If  the  battery  is  worked  at  a  high  current,  its  life  is 
short;  if  however,  it  is  discharged  at  a  low  rate,  its  life  should  be 
long.  In  all  cases  the  product  of  the  number  of  amperes  and 
the  number  of  hours  constitute  the  ampere-hours  of  energy 
produced. 


358 


MECHANICS  OF  THE  HOUSEHOLD 


Multiple  -  1J/2  Volts 
b 


Series-Multiple  -  6  Volts 
c 


Series-Multiple 
d 


6  Volts 


E 


Series-Multiple  -  6  Volts 

e 
FIG.  256. — Battery  combinations. 


Battery  Formation. — For 
ordinary  household  work  as 
that  of  operating  doorbells, 
etc.,  the  cells  which  form  a 
battery  are  joined  in  series, 
that  is  the  positive  or  car- 
bon pole  of  one  cell  is  joined 
B  to  the  zinc  or  negative  pole 
of  the  next.  The  cells  so 
connected  are  placed  in  cir- 
cuit with  the  bell  and  push 
button.  If  by  accident  the 
two  cells  of  a  battery  are 
joined  with  both  carbon 
poles  or  both  zinc  poles  to- 
gether the  battery  will  give 
out  no  current  because  the 
voltage  is  opposed. 

In  the  use  of  batteries  for 
ignition  as  for  gasoline  en- 
gines, automobiles,  etc.,  the 
arrangement  of  the  cells  has 
frequently  a  decided  in- 
fluence on  the  effect  pro- 
duced. In  Fig.  256  A  is 
represented  four  cells  joined 
in  series,  that  is  the  carbon 
or  +  poles  are  joined  with 
the  zinc  or  —  poles,  alter- 
nately. Connected  in  this 
manner  if  each  cell  gives  1.5 
volts  the  battery  will  give 
4  X  1.5  =  6  volts;  the  cur- 
rent, however,  will  remain 
as  that  of  a  single  cell.  If 
the  cells  singly  give  20  volts, 
the  battery  will  give  20  volts. 
When  cells  are  connected  in 
this  form  the  current  passes 


ELECTRICITY  359 

through  each  cell  in  turn  and  is  as  much  a  part  of  the  circuit 
as  the  wires.  Should  one  of  the  cells  be  "dead" — that  is  de- 
livering no  current — it  will  act  as  additional  resistance  and  the 
current  is  reduced. 

When  joined  in  multiple  or  parallel  connection  as  in  Fig.  256  B, 
in  which  all  similar  binding  posts  are  connected,  the  effect  is 
decidedly  different.  In  the  multiple  connection  .all  of  the  zincs 
are  joined  to  act  as  a  single  zinc  and  all  of  the  carbons  are  like- 
wise joined  and  act  as  a  single  carbon.  In  such  a  combination 
the  voltage  will  be  that  of  a  single  cell  1.5  volts,  but  the  amper- 
age will  be  four  times  that  of  a  single  cell  or  80  amperes. 

The  diagrams  and  following  descriptions  of  possible  combina- 
tions were  taken  from  a  bulletin  on  battery  connections  issued 
by  the  French  Battery  and  Carbon  Co. 

By  combining  the  series  and  multiple  connections,  as  shown  in 
Fig.  C,  both  the  voltage  and  current  can  be  increased  over  that 
delivered  by  one  cell.  Referring  to  the  figure,  it  is  seen  that 
in  each  of  the-  two  rows  of  four  cells  the  cells  are  connected 
in  series.  This  would  produce  6  volts  and  20  amperes  for  the 
series  of  four  which  may  now  be  assumed  as  a  unit,  so  that 
the  two  rows  can  be  imagined  as  two  large  cells,  each  of 
which  has  a  normal  output  of  20  amperes  at  6  volts.  Now 
by  connecting  the  similar  poles  of  two  such  large  cells  they 
are  in  multiple  and  we  get  an  increased  current  or  40  amperes 
and  6  volts,  which  is  the  capacity  of  the  eight  cells  connected 
as  shown  in  the  figure.  This  is  commonly  designated  as  a 
multiple-series  battery. 

Fig.  256  D  illustrates  a  multiple-series  connection  made  in  a 
different  manner,  but  which  produces  the  same  voltage  and 
current  as  the  above  mentioned.  In  Fig.  D,  two  cells  at  a  time 
are  connected  in  multiple,  and  these  sets  are  then  connected  in 
series.  The  capacity  of  each  set  of  two  is  40  amperes  at  1  J£  volts, 
and  as  these  four  sets  are  connected  in  series  the  total  output  of 
the  eight  cells  combined  is  6  volts  and  40  amperes,  the  same  as 
that  produced  by  the  connections  shown  in  Fig.  C. 

Fig.  E  shows  the  multiple-series  connection  illustrated  in  Fig. 
D,  applied  to  twelve  cells  in  which  four  sets  of  three  cells  each 
are  wired  in  series,  the  three  cells  of  a  set  being  in  multiple  so  that 
the  capacity  of  a  set  is  1%  volts  and  60  amperes.  By  connecting 


360  MECHANICS  OF  THE  HOUSEHOLD 

the  four  sets  in  series  as  shown,  the  total  capacity  will  be  60 
amperes  at  6  volts. 

The  use  of  the  series-multiple  connection  is  a  distinct  step 
forward  in  dry-cell  use.  The  arrangement  of  cells  shown  in  Figs. 
C  or  D  is  better  than  the  arrangement  in  Fig.  A,  in  just  the  same 
way  that  a  team  of  horses  is  better  than  a  single  horse.  One 
horse  pulling  a  load  of  2  tons  may  become  exhausted  in  one  hour, 
but  two  horses  pulling  that  same  load  may  work  continuously 
for  six  hours.  It  is  true  that  in  Fig.  C  there  are  twice  as  many 
cells  used  as  in  Fig.  A,  but  the  eight  cells  in  Fig.  C  will  do  from 
three  to  four  times  as  much  work  as  the  four  cells  in  Fig.  A.  In 
other  words,  while  more  cells  are  used  in  the  multiple-series 
arrangement,  the  amount  of  service  per  cell  is  greater  and  the 
service  is,  therefore,  cheaper  in  the  multiple-series  arrangement. 

Some  battery  manufacturers  sell  their  batteries  put  up  in  boxes, 
the  cells  being  connected  up  in  multiple-series  and  surrounded 
by  pitch  or  tar  to  keep  out  the  moisture.  This  has  certain 
.advantages  as  well  as  certain  disadvantages.  One  of  the  objec- 
tions to  this  method  of  putting  up  dry  cells  is  that  if  by  any 
chance  one  cell  out  of  the  eight  or  twelve  which  are  buried  in  the 
pitch  is  defective  it  will  run  all  of  the  cells  down,  and  being 
buried  offers  no  means  of  detection  or  removal.  It  is  not  pos- 
sible to  guarantee  absolutely  that  a  weak  cell  will  not  be  occa- 
sionally included  in  a  large  number,  so  dry  cells  may  be  expected 
to  vary  to  some  degree  among  themselves. 

It  is  interesting  to  know  the  effect  of  one  weak  cell  on  a  series- 
multiple  arrangement.  If,  for  example,  in  Fig.  C  or  Fig.  D, 
the  dotted  line  connecting  (a)  and  (6)  be  used  to  indicate  a  cell 
which  is  partly  short-circuited  by  internal  weakness  or  external 
defect  the  result  is  as  follows : 

In  the  arrangement  shown  in  Fig.  C,  where  one  cell  of  the 
upper  four  is  short-circuited,  the  lower  four  will  discharge  through 
the  upper  four  even  though  the  external  circuit  is  not  closed; 
that  is,  one  short-circuited  cell  will  cause  a  run-down  in  all  of  the 
cells.  In  Fig.  Z),  however,  one  short-circuited  cell  will  influence 
not  the  entire  set  but  the  other  one  to  which  it  is  directly  con- 
nected. There  is  thus  seen  to  be  an  advantage  in  the  arrange- 
ment of  Fig.  D  and  Fig.  E,  over  the  arrangement  in  Fig.  C. 

In  making  connections  between  cells  insulated  wire  should  be 


ELECTRICITY  361 

used,  or  special  battery  connectors  are  preferably  employed. 
The  ends  of  the  wires  or  connectors  and  the  binding  posts  must 
be  scraped  clean  so  that  good  electrical  connection  can  be  made 
between  the  two,  and  the  knurled  nuts  should  be  screwed  tight 
into  place.  Care  must  also  be  taken  that  the  pasteboard  covering 
around  the  battery  is  not  torn.  This  would  allow  contact  be- 
tween the  zinc  containers,  and  thus  short-circuit  the  cells.  The 
batteries  should  be  placed  so  that  the  zinc  cans  and  the  binding 
posts  of  any  cell  do  not  come  into  contact  with  any  other  cell. 
Vibration  might  cause  enough  motion  for  the  brass  terminal  to 
wear  through  the  pasteboard  of  the  neighboring  cell  and  make 
contact  with  the  zinc  can. 

Different  classes  of  work  require  different  amounts  of  current 
at  different  voltages  and  by  choosing  the  proper  combination  of 
series,  multiple,  or  series-multiple  connec- 
tions practically  every  requirement  can  be 
fulfilled.  For  electric  bells,  telegraph  instru- 
ments, miniature  lights,  toy  motors  with  fine 
wire  windings,  etc.,  series  connection  is  recom- 
mended for  the  reason  that  the  resistance  of 
the  external  circuit  is  high  and  a  large  volt- 
age is  necessary.  For  spark  coils,  magnets 
and  toy  motors  with  large  wire  windings,  mul- 
tiple or  series-multiple  connection  of  batteries  fIG-  257.— Battery 

f,pgt,  pr 

should  be  used  as  a  high  volt  age  is  not  required. 

For  some  work,  gas-engine  ignition  especially,  it  is  economical 
to  have  two  complete  sets  of  batteries,  either  of  which  can  be 
thrown  into  the  circuit  at  will,  so  that  while  one  set  is  delivering 
current  the  other  is  recuperating.  It  has  been  estimated  that 
by  using  two  sets  of  batteries,  properly  connected  to  give  the 
desired  current,  the  life  of  each  set  is  increased  about  four  times. 
Thus  it  is  seen  that  a  saving  of  50  per  cent,  is  effected  in  the  cost 
of  the  batteries. 

Battery  Testers. — The  " strength"  of  a  cell  is  determined  by 
the  amperes  of  current  it  is  capable  of  producing;  therefore,  a 
meter  that  will  indicate  the  amount  of  current  being  produced 
is  used  to  test  the  current  strength  of  the  cell.  Battery  testers 
are  made  to  indicate  voltage  or  amperage  and  sometimes  the 
instrument  is  made  to  indicate  both  volts  and  amperes.  As  ex- 


362 


MECHANICS  OF  THE  HOUSEHOLD 


plained  above,  the  voltage  of  a  cell  is  not  a  true  indicator  of  its 
strength.  The  ampere  meter  or  ammeter,  as  it  is  termed,  is  the 
proper  indicator  of  the  strength  of  the  cell. 

The  common  battery  tester  does  not  always  give  the  exact 
number  of  amperes  of  current,  but  it  indicates  the  relative 
strength  which  is  really  the  thing  desired.  When  the  current 
from  an  active  cell  is  once  shown  on  the  dial  of  the  tester,  any 
other  cell  of  the  same  intensity  will  be  indicated  in  like  amount. 

Electric  Conductors. — Covered  wire  for  carrying  electricity 
is  made  in  a  great  variety  of  forms  and  designated  by  names  that 
have  been  suggested  by  their  use.  These  wires  are  made  of  a 
single  strand  or  in  cables,  where  several  wires  are  collected, 
insulated  and  formed  into  a  single  piece.  Cables  may  contain 
any  number  of  insulated  wires. 

The  sizes  of  wires  are  determined  by  a  wire  gage.  In  the 
United  States  the  B.  &  S.  gage  is  used  as  the  standard  for  all 
wires  and  sheet  metal.  The  gage  originated  with  the  Brown  & 
Sharp  Mfg.  Co.  of  Providence,  R.  I.,  and  has  become  a  national 
standard  by  common  consent.  The  numbers  range  from  No. 
0000  to  No.  60.  The  size  of  wire  for  household  electrical  service 
ranges  from  No.  18  which  is  0.04  inch  in  diameter  to  No.  8 
which  is  0.128  inch  across.  The  carrying  capacities  in  amperes 
of  wires,  as  given  by  the  Underwriters'  table  of  sizes  from  No.  8 
to  No.  18,  are  as, follows: 


Wire 
gage 
No. 

Rubber 
insulation, 
amperes 

Other 
insulation, 
amperes 

Wire 
gNT 

Rubber 
insulation, 
amperes 

Other 
insulation, 
amperes 

8 

35 

50 

14 

15 

20 

10 

25 

30 

16 

6 

10 

12 

20 

25 

18 

3 

5 

Lamp  Cord. — The  flexible  cord  used  for  drop  lights,  connectors, 
portable  lamps,  extensions,  etc.,  is  made  of  two  cords  twisted  to- 
gether or  two  cords  laid  parallel  and  covered  with  braided  silk  or 
cotton.  The  conductors  consist  of  a  number  of  No.  30  B.  &  S. 
gage,  unannealed  copper  wires  twisted  into  a  cable  of  required 
capacity.  The  conductor  is  wound  with  fine  cotton  thread  over 
which  is  a  layer  of  seamless  rubber,  and  the  whole  is  covered  with 


ELECTRICITY  363 

braided  cotton  or  silk.  Lamp  cord  is  sold  in  three  grades,  old 
code,  new  code,  and  commercial,  which  vary  only  in  the  thickness 
and  quality  of  rubber  which  encloses  the  conductor. 

The  new  code  lamp  cord  is  identical  with  the  old  code  form 
except  that  it  is  required  by  the  National  Board  of  Fire  Under- 
writers to  be  covered  with  a  higher  quality  of  rubber  insulation 
than  was  used  in  the  old  form.  The  commercial  cord  is  not 
recognized  by  the  National  Board  of  Underwriters.  It  is  practic- 
ally the  same  as  that  described  but  does  not  conform  to  the  tests 
prescribed  for  the  new  code  cord. 

The  sizes  of  the  conductors  enclosed  in  the  lamp  cord  are  made 
equal  in  carrying  capacity  to  the  standard  wire  gage  numbers. 
The  sizes  ordinarily  used  are  No.  18  and  20  gage  but  they  are 
made  in  sizes  from  No.  10  to  No.  22  of  the  Brown  &  Sharp  gage. 

Portable  Cord. — This  is  a  term  used  to  designate  reinforced 
lamp  cord.  The  wires  are  laid  parallel  and  are  covered  as  with 
a  supplementary  insulation  of  rubber.  The  additional  insulation 
and  the  braided  covering  assumes  a  cylindrical  form.  The 
covering  is  saturated  with  weatherproof  compound,  waxed*  and 
polished. 

Annunciator  Wire. — This  wire  is  made  in  the  usual  sizes  and 
covered  with  two  layers  of  cotton  thread  saturated  with  a.  special 
wax  and  highly  polished.  As  the  name  implies  it  is  used  for  an- 
nunciators, door  bells  and  other  purposes  of  like  importance. 

Private  Electric  Generating  Plants. — The  conveniences  to  be 
derived  from  the  use  of  electricity  were  for  many  years  available 
only  by  those  who  lived  in  distributing  areas  covered  by  commer- 
cial electrical  generating  plants.  Except  in  towns  of  sufficient 
size  to  warrant  the  erection  of  expensive  light  and  power  systems 
or  along  the  lines  of  electric  power  transmission,  current  for 
domestic  purposes  was  not  obtainable. 

Within  a  comparatively  few  years  there  have  been  developed 
a  number  of  small  electric  generating  systems  that  are  suitable 
for  supplying  the  average  household  with  the  electric  energy  for 
all  domestic  conveniences.  The  combination  of  the  gasoline  en- 
gine, the  electric  dynamo  and  the  storage  battery  have  made  pos- 
sible generating  apparatus  that  is  operated  with  the  minimum  of 
difficulty  and  which  supplies  all  of  the  electric  appliances  that 
were  formerly  served  only  from  commercial  electric  circuits. 


364  MECHANICS  OF  THE  HOUSEHOLD 

An  electric  generating  system  is  commonly  termed  an  electric 
plant.  It  consists  of  an  engine  for  the  development  of  power, 
a  dynamo  for  changing  the  power  into  electricity  and — to  be  of 
the  greatest  service — a  storage  battery  for  the  accumulation  of 
a  supply  of  energy  to  be  used  at  such  times  as  are  not  convenient 
to  keep  the  dynamo  in  active  operation. 

Such  a  combination,  each  part  comprised  of  mechanism  with 
which  the  average  householder  is  unfamiliar,  seems  at  first  too 
great  a  complication  to  put  into  successful  practice.  Such,  how- 
ever, is  not  the  case.  The  operation  of  small  electric  generating 
plants  is  no  longer  an  experiment.  Their  general  use  testifies  to 
their  successful  service.  The  working  principles  are  in  most  cases 
those  of  elementary  physics  combined  with  mechanism,  the 
management  of  which  is  not  difficult  to  comprehend.  Such 
plants  are  made  to  suit  every  condition  of  application  and  at  a 
cost  that  is  condusive  to  general  employment. 

In  a  brief  space  it  is  not  possible  to  enter  into  a  detailed  discus- 
sion of  the  gasoline  engine,  the  electric  dynamo,  and  the  storage 
battery  with  the  various  appliances  necessary  for  their  operation; 
it  is,  therefore,  intended  to  give  only  a  general  description  of  the 
leading  features  of  eaoh.  The  manufacturers  of  such  plants 
furnish  to  their  customers  and  to  others  who  are  interested  de- 
tailed information  with  explicit  instructions  for  their  successful 
management. 

The  first  private  lighting  plants  were  made  up  of  parts  built 
by  different  manufacturers  and  assembled  to  form  generating 
systems  with  little  regard  to  their  adaptability.  A  gasoline 
engine  belted  to  a  dynamo  of  the  proper  generating  capacity  sup- 
plied the  electricity.  Neither  the  engines  nor  the  dynamos  were 
particularly  suited  to  the  work  to  be  performed,  yet  these  com- 
binations were  sufficiently  successful  to  command  a  ready  sale. 
The  energy  thus  generated  was  accumulated  in  a  storage  battery 
from  which  was  taken  the  current  for  a  lighting  and  heating  de- 
vice. Besides  the  generating  and  storage  apparatus  there  is 
required  in  such  a  system,  a  switchboard,  to  which  are  attached 
the  necessary  meters  and  switches  that  are  required  to  measure 
and  direct  the  current  to  the  various  electric  circuits. 

Foresighted  manufacturers,  comprehending  the  probable  future 
demand,  began  the  construction  of  the  various  parts,  suited  to 


ELECTRICITY 


365 


the  work  and  the  conditions  under  which  they  were  to  be  em- 
ployed. The  manufacture  of  apparatus,  designed  for  the  special 
service  and  composed  of  the  fewest  possible  parts,  has  reduced 
the  operating  difficulty  to  a  point  of  relative  simplicity.  Ex- 
perience in  the  use  of  a  large  number  of  these  plants  has  revealed 
to  the  maker  the  course  of  many  minor  difficulties  of  operation 
and  the  means  of  their  correction.  The  mechanism  has  been 
improved  to  prevent  possible  derangement  and  to  simplify  the 


FIG.  258. — Household  electric  generating  plant. 

means  of  control,  until  the  private  electric  plant  is  successfully 
employed  by  those  who  have  had  no  former  experience  with 
power-generating  machines. 

As  an  example  of  the  private  electric  plant  Fig.  258  shows 
the  apparatus  included  in  a  combined  engine,  dynamo  and  switch- 
board, connected  with  a  storage  battery.  The  relative  size  of 
the  machine  is  shown  by  comparison  with  the  girl  in  the  act  of 
starting  the  motor.  This  plant  is  of  capacity  suitable  for  sup- 
plying an  average  home  with  electricity  for  all  ordinary  domes- 
tic uses.  A  nearer  view  of  the  generating  apparatus  is  given 
in  Fig.  259  in  which  all  of  the  exterior  parts  are  named.  An 


366 


MECHANICS  OF  THE  HOUSEHOLD 


interior  view  of  the  generating  apparatus  is  given  in  Fig.  260, 
in  which  is  exposed  all  of  the  working  parts.  The  right-hand 
side  of  the  picture  shows  all  of  the  parts  of  the  gasoline  engine 
that  furnishes  the  power  for  driving  the  generator.  This  is  an 
example  of  an  air-cooled  gasoline  engine  in  which  the  excess  heat 
developed  in  the  cylinder  is  carried  away  by  a  drought  of  air. 
The  air  draft  is  induced  by  the  flywheel  of  the  engine,  which  is 
constructed  as  a  fan.  The  blades  of  the  fan,  when  in  motion,  are 


OPPING  SWITCH 


BATTERY  IEAOS 


FIG.  259. — Combined  motor,  electric  generator  and  switchboard. 

so  set  as  to  draw  air  into  the  top  of  the  engine  casing  and  ex- 
haust it  from  the  rim  of  the  wheel.  The  air  in  passing  takes  up 
the  heat  in  excess  of  that  necessary  for  the  proper  cylinder  tem- 
perature. This  form  of  cylinder  cooling  takes  the  place  of  the 
customary  water  circulation  and  thus  eliminates  its  attending 
sources  of  trouble.  In  principle  the  engine  is  the  same  as  is 
employed  in  automobiles  and  other  power  generation. 

On  the  left-hand  side  is  seen  the  dynamo  and  switchboard. 


ELECTRICITY 


367 


The  dynamo  armature  is  attached  to  the  crankshaft  of  the  engine 
by  which  it  is  rotated  in  a  magnetic  field  to  produce  the  desired 
amount  of  electricity.  The  brushes,  in  contact  with  the  com- 
mutator, conduct  the  electricity  as  it  is  generated  in  the  armature, 
which  after  passing  through  the  switchboard  is  made  available 
from  the  two  wires  at  the  top  of  the  board  marked  "light  and 
power  wires."  These  wires  are  connected  with  the  storage  bat- 
tery and  also  to  the  house  circuits  through  which  the  current  is 
to  be  sent. 


FIG.  260. — Details  of  motor,  electric  generator  and  switchboard. 

Referring  to  the  switchboard  of  Fig.  259,  the  three  switches 
and  the  ammeter  comprise  the  necessary  accessories.  The  start- 
ing switch  is  so  arranged  that  by  pressing  the  lever  a  current  of 
electricity  from  the  storage  battery  is  sent  through  the  dynamo. 
The  dynamo  acting  as  a  motor  starts  the  engine.  When  the 
engine  has  attained  its  proper  speed  its  function  as  a  dynamo 
overcomes  the  current  pressure  from  the  battery  and  sends  elec- 
tricity into  the  cells  to  restore  the  expended  energy,  or  if  so  de- 
sired the  current  may  be  used  directly  from  the  dynamo  for  any 


368  MECHANICS  OF  THE  HOUSEHOLD 

household  purpose.  The  box  enclosing  the  switch  contains  a 
magnetic  circuit-breaker  so  constructed  that  when  the  battery  is 
completely  charged  the  switch  automatically  releases  its  contact 
and  stops  the  engine. 

The  " stopping  switch"  at  the  right  of  the  board  and  the 
" switch  for  light  and  circuit"  on  the  left  are  used  respectively 
for  stopping  the  engine  and  for  opening  and  closing  the  house 
circuits. 

The  meter  performs  a  multiple  function,  in  that  it  shows  at 
any  time  the  condition  of  charge  in  the  storage  battery,  the  rate 
at  which  current  is  entering  or  leaving  the  battery  and  also  acts 
to  stop  the  engine  when  the  battery  is  charged.  At  any  time  the 
pointer  reaches  the  mark  indicated  in  the  picture,  the  ignition 
circuit  is  automatically  broken  and  the  engine  stops.  The  fuses 
on  the  board  in  this  case  perform  the  same  function  as  those  al- 
ready described. 

Storage  Batteries. — These  batteries  have  already  been  men- 
tioned as  secondary  batteries.  They  are  sometimes  called  elec- 
tric accumulators.  The  electricity  .is  stored  or  accumulated,  not 
by  reason  of  the  destruction  of  an  electrode  as  in  the  primary 
cell  but  by  the  chemical  change  that  takes  place  in  the  plates  as 
the  charging  current  is  sent  through  the  cell.  When  the  battery 
is  discharged,  the  current  from  the  dynamo  is  sent  through  the 
battery  circuit  in  the  reverse  direction  to  that  of  the  discharge 
and  the  plates  are  restored  to  their  original  condition.  The 
action  that  takes  place  in  charging  and  discharging  is  due  to 
chemical  changes  that  take  pjace  in  the  plates  and  also  in  the 
solution  or  electrolyte  in  which  the  plates  are  immersed. 

There  are  two  types  of  storage  batteries,  those  made  of  lead 
plates  immersed  in  an  acid  electrolyte  and  the  Edison  battery 
which  is  composed  of  iron-nickel  cells  immersed  in  a  caustic 
potash  electrolyte.  The  former  type  is  most  commonly  used 
and  is  the  one  to  be  described. 

The  lead-plate  cell  illustrated  in  Fig.  262  shows  all  of  the 
parts  of  a  working  element.  The  plates  are  made  in  the  form 
of  lead  grids  which  when  filled  to  suit  the  requirements  of  their 
action,  form  the  positive  and  negative  electrodes.  The  negative 
plates  are  filled  with  finely  divided  metallic  lead  which  when 
charged  are  slate  gray  in  color.  The  positive  plates  are  filled 


ELECTRICITY  369 

with  lead  oxide.  When  charged  they  are  chocolate  brown  in 
color.  In  the  figure  there  are  three  positive  and  four  negative 
plates  which  together  form  the  element,  then  with  their  sepa- 
rators are  placed  in  a  solution  of  sulphuric  acid  electrolyte.  The 
separators  are  thin  pieces  of  wood  and  perforated  rubber  plates 
that  keep  the  positive  and  negative  plates  from  touching  each 
other  and  keep  in  place  the  disintegration  produced  by  the 
electro-chemical  action  of  the  cell. 

The  unit  of  electric  capacity  in  batteries  is  the  ampere-hour. 
The  cell  illustrated  will  accumulate  80  ampere-hours  of  energy. 
It  will  discharge  an  ampere  of  current  for  80 
hours.  If  desired  it  may  be  discharged  at  the 
rate  of  two  amperes  for  40  hours,  or  four  amperes 
for  20  hours,  or  at  any  other  rate  of  amperes  and 
hours,  the  product  of  which  is  80.  The  number 
of  ampere-hours  a  cell  will  accumulate  will  depend 
on  the  area  of  the  positive  and  negative  plates; 
large  cells  will  store  a  greater  number  of  ampere- 
hours  than  those  of  small  size. 

The  cells,  no  matter  what  size,  give  an  aver- 
age electric  pressure  of  2  volts. 

The  plates  are  joined  by  heavy  plate-straps 
connecting  all  of  the  positives  on  one  end  and 
all  of  the  negative  kind  on  the  opposite  end.  To 
insure  rigidity  the  two  sets  are  secured  to  the  rub- 
ber cover  by  locknuts.  In  this  cell  the  plates  are 
suspended  from  the  cover.  The  plate  terminals  FIG.  261.- 

,,  i  Hydrometer    for 

are  made  of  heavy  lead  connectors  that  wnen  testing  storage 
formed  into  a  battery  are  joined  together  with  battery  electro- 
lead  bolts  and  nuts. 

The  electrolyte  is  a  solution  of  pure  sulphuric  acid  in  distilled 
water  and  on  its  purity  depends,  in  a  great  measure,  its  action 
and  length  of  life.  The  electrolyte  is  made  of  a  definite  density 
which  is  expressed  as  its  specific  gravity.  When  fully  charged 
the  electrolyte  will  test  1220  by  the  hydrometer.  That  is,  it 
will  be  1.220  heavier  than  water.  When  discharged  it  will  test 
by  the  hydrometer  1185.  This  means  that  in  discharging  the 
density  has  been  reduced  to  1.185  that  of  water.  The  chemical 
change  in  the  electrolyte  is,  therefore,  an  important  part  of  the 

24 


370  MECHANICS  OF  THE  HOUSEHOLD 

charge  and  discharge  of  the  cell.  The  density  of  an  electrolyte 
may  be  determined  by  a  hydrometer  such  as  Fig.  261 .  This  is  an 
ordinary  glass  hydrometer  such  as  is  used  for  determining  the 
density  of  fluids,  enclosed  in  a  glass  tube,  to  which  is  attached 
a  rubber  bulb.  The  point  of  the  tube  is  inserted  into  the  open- 
ing at  the  top  of  the  cell  and  the  electrolyte  drawn  into  the  tube 
by  the  reopening  of  the  collapsed  bulb.  The  density  is  then  read 
from  the  stem  of  the  hydrometer. 

The  Pilot  Cell. — In  order  to  make  apparent  this  density  of 
the  electrolyte  without  the  necessity  of  its  measurement  with  a 
hydrometer,  one  cell  of  the  battery  is  provided  with  a  gage  as 
that  of  Fig.  262.  This  is  an  enlargement  of  the  end  of  the  jar 
in  which  floats  a  hollow  glass  ball  of  such  weight  that  it  will  at 
any  time  indicate  by  its  position  the  relative  density  of  the 
solution.  When  the  cell  is  charged  the  ball  stands  at  the  top 
of  the  gage  and  indicates  a  density  1220;  when  discharged  it  is 
at  the  bottom  and  expressed  by  its  position  a  density  of  1185. 
The  electrolyte  densities  are  the  indicators  of  the  conditions  of 
charge.  The  ball  by  its  position  shows  at  a  glance  the  quantity 
of  electricity  in  the  battery. 

The  voltage  usually  employed  in  household  electric  plants  is 
that  of  a  battery  composed  of  16  cells.  Since  the  normal  voltage 
of  a  storage  cell  is  2  volts  such  a  battery  joined  in  series  is  32 
volts.  This  voltage  for  the  purpose  fulfills  all  ordinary  condi- 
tions and  is  generally  employed.  A  battery  of  16  cells,  of 
80-ampere-hour  capacity,  will  deliver  current  of  1  ampere  for 
80  hours  at  32  volts  intensity.  A  20-watt  lamp  on  a  32-volt 
circuit  requires  %  ampere  for  its  operation.  The  battery  will, 
therefore,  keep  lighted  one  such  lamp  for  96  hours,  or  four  20- 
watt  lamps  may  be  lighted  continuously  for  24  hours,  or  eight 
lamps  for  12  hours,  before  recharging. 

Aside  from  its  ability  to  supply  the  required  light  for  the 
average  home,  it  furnishes  energy  sufficient  for  heating  a  flat- 
iron  or  other  heating  apparatus,  to  operate  motors  for  pumping 
water,  driving  a  washing  machine  or  any  other  of  the  domestic 
requirements. 

Such  plants  are  made  in  sizes  to  suit  any  condition  of  require- 
ment. In  large  establishments  a  larger  motor  generator  and 
battery  will  be  necessary  with  which  to  generate  and  store  the 


ELECTRICITY 


371 


required  electricity  but  in  any  case  suitable  apparatus  is  to  be 
obtained  to  meet  any  requirement  of  light,  heat  or  power 
developed. 


BOLT 
CONNEC 


POSITIVE 
TERMINAL^ 


SEMI-HARD 
RUBBER  COVER 


'EGATIVE 
TERMINAL 


WOOD 
TARATOR. 


NEGATIVC 
PLATE 

>LATE 

^    ^r       SUPPORT  LOCK 
^POSITIVE  PLATE 

HARD 
RUBBER  SEPARATOR 

FIG.  262. — Electric  storage  cell. 

National  Electrical  Code. — The  details  governing  the  size,  the 
manner  of  placing  and  securing  wires  in  buildings  is  included  in 
the  regulations  published  by  the  National  Board  of  Fire  Under- 
writers as  the  National  Electric  Code.  Likewise  the  mechanical 
construction  of  all  apparatus  dealing  with  electric  distribution 
is  definitely  specified  so  that  manufacturers  furnish  reliable 
materials  for  all  requirements.  In  the  specifications  for  furnish- 


372  MECHANICS  OF  THE  HOUSEHOLD 

ing  buildings  with  the  use  of  electricity,  descriptions  are  made 
of  the  desired  types  and  styles  of  the  switches  and  various  other 
fixtures  to  suit  the  requirements. 

Electric  Light  Wiring. — In  the  equipment  of  a  house  for  the 
use  of  electricity,  the  wiring,  together  with  distributing  panel, 
the  various  outlets,  receptacles,  switches,  and  other  appliances 
that  make  up  the  system,  is  of  more  than  passing  consequence. 
In  the  construction  of  the  electric  system  it  is  important  that  the 
wires  and  their  installation  be  done  in  a  manner  to  meet  every 
contingency. 

The  following  descriptions  for  electric  house  wiring  were  taken 
from  a  set  of  specifications  published  by  the  Bryant  Electric  Co. 
as  applying  to  buildings  of  wood  frame  construction.  The  speci- 
fications serve  as  explanations  for  the  appliances  required  in  an 
ordinary  dwelling.  The  specifications  are  for  the  least  expensive 
form  of  good  practice  in  wiring  for  frame  buildings.  They  would 
not  be  permitted  in  large  cities  where  further  protection  from  fire 
is  required  and  where  more  rigid  rules  are  demanded  by  the 
Board  of  Fire  Underwriters. 

1.  SYSTEM. — The  circuit  wiring  shall  be  installed  as  a  two- wire  direct 
current  or  alternating  system.  Not  more  than  16  outlets  or  a  maximum  of 
660  watts  shall  be  placed  on  any  one  circuit,  allowing  110  watts  for  each 
baseboard  plug  connection  or  extension  outlet  and  55  watts  for  each  16 
candlepower  lamp  indicated  at  the  various  wall  and  ceiling  outlets  on  plans. 
All  wiring  shall  be  installed  as  a  concealed  knob-and-tube  system. 

The  type  of  wiring  is  designated  as  a  two-wire  direct  or  alter- 
nating current  system  in  order  that  there  shall  be  no  doubt  as 
to  the  method  of  wiring  to  be  used.  There  are  other  methods 
that  might  be  employed  that  need  not  be  discussed  here. 

The  16  outlets  mentioned  are  intended  to  cover  all  lamps  or 
plug  attachments  that  are  to  be  used  for  heaters,  fans,  motors; 
or  any  other  electric  device.  The  660  watts  at  110  volts  pres- 
sure will  require  6  amperes  in  the  main  wires  of  the  circuit, 
which  is  the  maximum  current  the  wires  are  intended  to  carry. 
This  does  not  mean  that  110-watt  lamps  might  not  be  used 
but  that  no  single  circuit  shall  carry  lamps  that  will  aggregate 
more  than  660  watts. 

The  concealed  knob-and-tube  system  mentioned  is  illustrated 
in  Figs.  263  and  264,  in  which  the  wires  which  pass  through  joists 


ELECTRICITY 


373 


and  studding  are  to  be  insulated  by  porcelain  tubes  and  those 
wires  which  lay  parallel  to  these  members  are  to  be  fastened  to 

porcelain  knobs  which  are 
secured  by  screws  to  the  wood 
pieces  to  prevent  any  possi- 
bility of  coming  into  contact 
with  electric  conducting  ma- 
terials. 

2.  OUTLETS. — At  each  and  every 

"?**•  T11'  rling<  Tptacle  ^ 

outlets.  other  outlet  shown  on  plans,  install 

a  metal  outlet  box  of  a  style  most 

suitable  for  the  purpose  of  the  outlet.  All  outlet  boxes  must  be  rigidly 
secured  in  place  by  approved  method  and  those  intended  for  fixtures  shall 
be  provided  with  a  fixture  stud,  or  in  the  case  of  large  fixtures,  a  hanger  to 
furnish  support  independent  of 
the  outlet  box. 

Outlet  Boxes.— For  the 
safe  and  convenient  accom- 
modation of  switches,  re- 
ceptacles or  other  connec- 
tions in  the  walls  and  ceilings 
of  a  building,  outlet  boxes 
are  used  as  a  means  of  secur- 
ing the  wire  terminals  to  the 
receptacles.  These  boxes 
are  made  in  a  number  of 
forms  for  general  application. 
One  style  is  shown  in  Fig. 
265.  The  boxes  are  made 
of  sheet  steel  and  arranged 
to  be  secured  in  place  with 
screws.  The  box  is  further 

provided   with  screw  fasten-  FIG.    264. — This    shows    the    knob-and- 

nox  to    whirh    thp  <*witf»h  or  tube  system  of  securing  the  wires  in  parti- 

r  tions  and  the  manner  of  fastening  metal 

receptacle     may     be     firmly  "cut  out"  boxes;  for  switch,  attachments, 

attached.  plugs' etc' 

3.  INSTALLATION  OF  WIRES,  ETC.— All  wires  shall  be  rigidly  supported  on 
porcelain  insulators  which  separate  the  wire  at  least  1  inch  from  the  sur- 


374  MECHANICS  OF  THE  HOUSEHOLD 

face  wired  over.  Wires  passing  through  floors,  studding,  etc.,  shall  be  pro- 
tected with  porcelain  tubes,  and  where  wires  pass  vertically  through  bottom 
plates,  bridging,  etc.,  of  partitions,  an  extra  tube  shall  be  used  to  protect 
wires  from  plaster  droppings.  Wires  must  be  supported  at  least  every  4 
feet  and  where  near  gas  or  water  pipes  extra  supports  shall  be  used.  All 
porcelain  material  shall  be  non-absorptive  and  broken  or  damaged  pieces 
must  be  replaced.  Tubes  shall  be  of  sufficient  length  to  bush  eutire  length 
of  hole.  At  outlets  the  wires  shall  be  protected  by  flexible  tubing,  the  same 
to  be  continuous  from  nearest  wire  support  to  inside  of  outlet  box.  Wires 
installed  in  masonry  work  shall  be  protected  by  approved  rigid  iron  conduit 
which  shall  be  continuous  from  outlet  to  outlet. 

The  method  and  reasons  for  supporting  the  wires  described 
above  are  as  have  already  been  mentioned  under  item  1.     The 
reason  for  extra  supports  near  gas  pipes  and  water 
pipes  is  as  a  precaution  against  the  possibility  of 
short-circuiting. 


4.  CONDUCTORS. — Conductors  shall  be  continuous  from 
outlet  to   outlet  and  no  splices  shall  be  made  except  in 
outlet  boxes.     No  wire  smaller  than  No.  14  B.  &  S.  gage 
shall  be  used  and  for  all  circuits  of  100  feet  or  longer, 
FIG    265 O  t     "^°*    ^'  B.  &  S.  gage  or  larger  shall  be  used.     All  con- 
let  box.          ductors  of  No.  8  B.  &  S.  gage  or  larger  shall  be  stranded. 
Wires  shall  be  of  sufficient  length  at  outlets  to  make  con- 
nection to  apparatus  without  straining  connections.     Splices  shall  be  made 
both   mechanically  and   electrically  perfect,  and  the  proper  thickness  of 
rubber  and  friction  tape  shall  be  then  applied. 

Continuous  conductors  are  required  because  of  the  possibility 
of  defects  in  the  joints  of  spliced  wire. 

5.  POSITION  OF  OUTLETS. — Unless  otherwise  indicated  or  directed,  plug 
receptacles  shall  be  located  just  above  baseboard;  wall  brackets,  5  feet  above 
finished  floor  in  bedrooms,  and  5  feet  6  inches  in  all  other  rooms;  wall 
switches,  4  feet  above  finished  floors.     All  outlets  shall  be  centered  with  re- 
gard to  panelling,  furring,  trim,  etc.,  and  any  outlet  which  is  improperly 
located  on  account  of  above  conditions  must  be  corrected  at  the  contractor's 
expense.     All  outlets  must  be  set  plumb  and  extend  to  finish  of  wall,  ceil- 
ing or  floor,  as  the  case  may  be,  without  projecting  beyond  same. 

6.  MATERIALS. — All  materials  used  in  carrying  out  these  specifications 
shall  be  acceptable  to  the  National  Board  of  Fire  Underwriters  and  to  the 
local  department  having  jurisdiction.     Where  the  make  or  brand  is  speci- 
fied or  where  the  expression  "equal  to"  is  used,  the  contractor  must  notify 
the  architect  of  the  make  or  brand  to  be  used  and  receive  his  approval  before 
any  of  said  material  is  installed.     Where  a  particular  brand  or  make  is 
distinctly  specified,  no  substitution  will  be  permitted. 


ELECTRICITY  375 

7.  GRADE  OF  WIRE.— The  insulation  of  all  conductors  shall  be  rubber, 
with  protecting  braids,  which  shall  be  N.E.C.  Standard  (National  Electrical 
Code  Standard). 

8.  OUTLET  BOXES. — Outlet  boxes  shall  be  standard  pressed  steel,  knock- 
out type  and  shall  be  enameled. 

9.  LOCAL  SWITCHES.— Local  wall  switches  shall  be  two-button  flush  type 
completely  enclosed  in  a  box  of  non-breakable  insulating  material  with 
brass  beveled-edge  cover  plate  finished  to  match  surrounding  hardware. 

Fig.  269  shows  the  various  forms  and  grades  of  switches  that 
there  are  on  the  market.  The  screws  which  attach  the  plate  to 
the  switch  enter  bushings  that  are  under  spring  tension  thereby 
preventing  defacement  of  the  plate  by  overtightening  of  the 
screws.  Single-pole  is  to  be  used  where  the  load  will  not  be  in  ex- 
cess of  660  watts;  double-pole  to  be  used  where  the  load  is  more 
then  660  watts  or  where  for  any  other  reason  it  is  desirable  to 
break  the  current  at  both  wires.  Three-point  switches  are  to  be 
used  when  a  light  or  group  of  lights  is  to  be  controlled,  as  hall 
lights  that  may  be  lighted  or  extinguished,  from  either  the  top 
or  at  the  bottom  of  a  stairway.  Four-point  switches  are  to  be 
used  between  and  two,  three-point  switches  to  control  additional 
lights.  Where  two  or  more  switches  are  placed  together  an 
approved  gang  plate  is  to  be  provided  which  designates  the  use 
of  each  switch.  Where  indicated  on  the  plan,  clothes  closets 
shall  be  equipped  with  automatic  door  switch  to  connect  the  light 
when  the  door  is  open. 

10.  PILOT  LIGHTS. — Switches  controlling  cellar,  attic  and  porch  lights 
shall  have  pilot  lamp  in  parallel  on  the  load  side  of  the  switch.     The  switch 
in  Fig.  3  requires  for  its  installation  a  two-gang  outlet  box.     The  ruby  bull's- 
eye  which  covers  the  lamp  is  practically  flush,  extending  from  the  wall  no 
further  than  the  buttons  of  the  switch. 

Pilot  lights  are  intended  to  indicate  the  operation  of  other 
lights  or  apparatus  that  cannot  be  directly  observed. 

The  term  bull's-eye  applies  to  a  colored-glass  button  covering 
a  miniature  lamp  which  burns  whenever  a  light  is  used  which  is 
apt  to  be  forgotten  and  allowed  to  burn  for  a  longer  time  than 
necessary. 

11.  PLUG  RECEPTACLES. — Plug  receptacles  shall  be  of  the  disappearing- 
door  type,  with  beveled-edge  brass  cover  plate  finished  to  match  surround- 
ing hardware  (see  Fig.  266).     In  this  receptacle  the  doors  are  pushed  inward 
by  the  insertion  of  the  plug  and  upon  its  withdrawal  close  automatically, 


376  MECHANICS  OF  THE  HOUSEHOLD 

effectually  excluding  dirt  and  concealing  the  live  terminals.     It  is  the  latest 
and  best  plug  receptacle  obtainable. 

Plug  receptacles  are  the  attachments  for  the  terminal  pieces 
of  plugs,  which  temporarily  connect  portable  lamps,  electric  fans 
or  other  devices,  they  are  made  in  many  forms. 

12.  WALL    AND    CEILING   SOCKETS. — One-light  ceiling  receptacles  shall 
be  of  a  type  to  fit  standard  3^-inch  or  4-inch  outlet  boxes.     Wall  sockets 
shall  be  of  the  insulated  base  type.     Sockets  in  cellars  shall  be  made  entirely 
of  porcelain  and  of  the  pull  type.     All  lamp  sockets  used  in  fulfilling  these 
specifications  shall  have  an  approved  rating  of  660  watts,  250  volts. 

13.  DROP  LIGHTS. — Drop  lights  shall  consist  of  the  necessary  length  of 
reinforced  cord  supported  by  an  insulated  rosette  with  brass  base  and  cover; 
the  latter  to  cover  4-inch  outlet  box,  and  furnished  with  a  key  socket  com- 
plete with  a  2^-inch  shade-holder.     Each  drop  cord  shall  have  an  adjuster. 

14.  HEATER  SWITCH,  PILOT  AND  RECEPTACLE. — Heating  device  outlets 
shall  be  equipped  with  combination  of  switch,  pilot  light  and  receptacle  with 
plug  and  spare  pilot  lamp. 

15.  SERVICE  SWITCH. — The  service-entrance  switch  shall  be  30  amperes, 
porcelain  base  with  connections  for  plug  fuses. 

INSTALLATION  OF  SERVICE  SWITCH. — Service  switch  shall  be  installed  in 
a  moisture-proof  metal  box  with  hinged  door. 

PANEL  CABINET. — The  distributing  panel  cabinet  shall  be  of  steel  not 
less  than  No.  12  gage  reinforced  with  angle  iron  frames,  which  shall  be  se- 
curely riveted  in  place.  Cabinet  shall  be  larger  than  panel  to  give  at  least 
4-inch  wire  space  around  panel  and  shall  be  given  at  least  two  coats  of  mois- 
ture-repellant  paint. 

DISTRIBUTING  PANEL. — The  distributing  panel  shall  consist  of  two-wire 
125-volt  branch  cutouts,  two-wire  125-volt  porcelain-base  panel-board 
units,  two-wire  125-volt  porcelain-base  deadfront  panel-board  units.  The 
distributing  panel  shall  be  surrounded  with  an  ebony  asbestos  or  slate 
partition  ^  inch  thick  which  will  form  a  wire  space  around  panel. 

FUSES. — All  fuses  for  branch  circuits  shall  be  not  more  than  10  amperes 
capacity.  The  contractor  shall  furnish  the  owner  with  150  per  cent,  of 
required  number  of  125--volt  plug-type  fuses  for  complete  installation. 

PANEL  TRIM  AND  DOOR. — The  panel  trim  and  door  shall  be  of  steel,  with 
brass  cylinder  lock  and  concealed  hinges,  all  furnished  under  this  contract. 
A  directory  of  circuits  arid  outlets  served  by  panel  shall  be  enclosed  in  glass 
with  metal  frame,  mounted  on  inside  of  panel  door. 

HARDWARE. — All  hardware  furnished  under  this  contract  shall  match  in 
quality  and  finish  other  adjacent  hardware. 

THREE-WAY  CONTROL. — The  nearest  outlet  at  top  and  bottom  of  all  stairs 
and  in  entrance  hall  shall  be  controlled  by  three-way  switches  located  on 
separate  floors  where  directed. 

ELECTROLIER  CONTROL. — Wherever  there  are  ceiling  outlets  for  fixtures 
having  three  or  more  sockets  controlled  by  wall  switches  three  wires  shall 


ELECTRICITY  377 

be  run  between  the  switch  box  and  the  outlet  to  permit  the  use  of  electrolier 
switches. 

DINING-ROOM  CIRCUIT. — Furnish  and  install  in  dining-room,  where  indi- 
cated on  plans,  an  approved  floor  box  containing  an  approved  25-ampere 
plug  receptacle.  The  wires  connecting  this  receptacle  to  the  center  of 
distribution  shall  be  No.  10  B.  &  S.  gage.  Furnish  and  deliver  to  whom  di- 
rected an  approved  multiple-connection  block  consisting  of  three  individually 
fused  plug  receptacles.  The  connection  between  the  plug  receptacle  and 
this  block  shall  be  made  by  means  of  10  feet  of  No.  10  B.  &  S.  approved  silk- 
covered  portable  cord  with  an  approved  20-ampere  cord  connector  2  feet 
from  the  multiple  block. 

HOUSE  FEEDERS. — The  size  of  the  feeder  from  the  service  switch  to  the 
panel  board  shall  be  figured  in  accordance  with  the  National  Code  rules  for 
carrying  capacity,  allowing  for  all  circuits  being  fully  loaded.  The  feeder 
shall  be  of  sufficient  size,  however,  to  confine  the  drop  in  voltage,  with  all 
lights  in  circuit  to  1  per  cent,  of  the  line  voltage. 

SERVICE  CONNECTION. — Make  extension  of  house  feeder  overhead  to 
lighting  company's  mains  and  make  all  connections  complete  to  the  satis- 
faction of  the  light  company  and  the  architect.  Furnish  and  install  the 
necessary  frame  or  backboard  for  meter. 

CALL  BELLS. — The  contractor  shall  furnish,  install  and  connect  all  push 
buttons,  bells,  buzzers  and  annunciators,  as  shown  on  plans  or  therein 
described.  All  wiring  shall  be  cleated  in  joists,  studs,  etc.,  with  insulated 
staples.  Damp  places,  metal  pipes  of  all  descriptions,  flues,  etc.,  must  be 
avoided  and  wire  fastenings  must  be  applied  in  such  a  way  that  insulation 
is  not  damaged.  No  splices  shall  be  made  where  same  will  not  be  accessible 
at  any  time  after  completion  of  building.  Wires  shall  not  be  smaller  than 
No.  18  B.  &  S.  gage  and  shall  be  damp-proof  insulated.  Bells,  buzzers,  but- 
tons, etc.,  shall  be  of  approved  make.  Push  button  for  main  entrance  door 
shall  be  provided  with  ornamental  place  with  approved  finish.  Push  button 
in  dining-room  shall  consist  of  combination  floor  push,  with  necessary  length 
of  flexible  cord  and  approved  portable  foot  push.  Furnish  and  install 
where  directed  three  cells  of  carbon  cylinder  battery  in  a  substantial  cabinet. 

BURGLAR  ALARM. — Furnish  and  install  complete  burglar  alarm  system 
consisting  of  the  necessary  wires,  window  springs,  door  springs,  night  latch 
cutout  for  front  door,  bell,  batteries,  cabinet,  interconnection  strip,  etc., 
and  everything  required  for  a  complete  open-circuit  system.  Each  window 
sash  and  door  throughout  the  building  shall  be  equipped  with  contact 
spring  of  approved  make  and  all  springs  on  same  side  of  building  on  each 
floor  shall  be  wired  on  one  circuit  and  terminated  on  single-pole  knife  switch 
on  interconnection  strip.  The  interconnection  strip  shall  be  located  as 
directed  and  shall  have  cutout  switches  for  each  circuit  as  well  as  a  double- 
pole  battery  switch.  The  battery  shall  consist  of  at  least  three  dry  cells  in 
suitable  cabinet  placed  where  directed  and  both  positive  and  negative  leads 
shall  be  carried  direct  to  interconnection  strip.  The  burglar-alarm  wires 
shall  be  not  less  than  No.  16  B.  &  S.  gage,  insulated  and  installed  as  speci- 
fied for  call  bells. 


378  MECHANICS  OF  THE  HOUSEHOLD 

INTERCOMMUNICATING  TELEPHONES. — Furnish  and  install  an  intercom- 
municating telephone  system  complete  with  all  telephone  sets,  wiring, 
batteries,  etc.  All  wires  to  be  cables  containing  one  pair  of  No.  22  B.  &  S. 
gage  conductors  for  each  station  and  a  pair  of  No.  16  B.  &  S.  gage  conductors 
for  talking  and  ringing  battery  respectively.  Each  pair  of  wires  shall  be 
twisted  and  all  pairs  shall  be  twisted  around  each  other  to  eliminate  cross 
talk  and  inductive  noises.  The  wires  shall  be  silk  insulated,  with  a  moisture 
repellent  of  beeswax  or  varnish  and  the  whole  covered  with  a  lead  sheath 
at  least  ^4  inch  in  thickness.  Where  cables  terminate  in  outlet  boxes  they 
shall  be  fanned  out  and  laced  in  an  orderly  manner  and  secured  to  connect- 
ing terminals,  one  of  which  shall  be  provided  for  each  wire.  Install  where 
directed  in  an  approved  cabinet  at  least  four  cells  of  dry  battery  each,  for 
talking  and  ringing  purposes. 

INSTALLATION  OP  INTERPHONE  CABLE. — Intercommunicating  cables 
shall  be  supported  with  pipe  straps  and  liberal  clearance  shall  be  observed 
where  near  steam  or  other  pipes. 

Automatic  Door  Switch. — Where  indicated  on  the  plan,  clothes 
closets  shall  be  equipped  with  automatic  door 
switch  to  connect  the  light  when  the  door  is  open. 
Fig.  266  is  placed  in  the  door  frame  in  such 
position  that  electric  contact  is  made  by  release  of 
the  projecting  pin  as  the  door  is  opened.  When 
the  door  is  closed,  the  pin  is  depressed  and  the  light 
is  extinguished 

Plug  Receptacles. — Plug  receptacles  shall  be 
selected  from  the  styles  shown  in  Figs.  267,a,  b,  c 
or  d. 

FIG.  266.—  pjg  267,a  is  the  disappearing-door  type  with 
door  switch.  beveled-edge  brass  cover  plate  finished  to  match 
surrounding  hardware.  In  this  receptacle  the  doors 
are  pushed  inward  by  the  insertion  of  the  plug  and  upon  its 
withdrawal  close  automatically,  effectually  excluding  dirt  and 
concealing  the  live  terminals.  It  is  the  latest  and  best  plug  re- 
ceptacle obtainable. 

Fig.  267,6  is  of  the  Chapman  type  with  beveled-edge  brass 
cover  plate  finished  to  match  surrounding  hardware.  In  this 
receptacle  the  doors  open  outward  but  are  flush  whether  the  plug 
is  in  or  out. 

Fig.  267,c  is  of  the  screw-plug  type  with  beveled-edge  brass 
cover  plate  finished  to  match  surrounding  hardware.  By  many 


ELECTRICITY 


379 


FIG.  267.— Styles  of  plug  receptacles. 


FIG.  268.— Heating-device  receptacles. 


380 


MECHANICS  OF  THE  HOUSEHOLD 


this  is  preferred  for  apartment  use  as  it  will  receive  any  style  of 
Edison  attachment  plug. 

Fig.  267,  d  is  of  the  removable-mechanism  type  with  beveled- 
edge  brass  cover  plate  finished  to  match  surrounding  hardware. 


(c) 


FIG.  269. — Service  switches. 


The  mechanism  of  this  receptacle  is  exchangeable  with  the  mech- 
anism of  the  double-pole  switch  as  shown  in  Fig.  270,c. 

Heater   Switch,  Pilot  and  Receptacle. — Heating-device  out- 
lets shall  be  equipped  with  combination  of  switch,  pilot  light  and 


FIG.  270. —  Local  wall  switches. 


receptacle  with  plug  and  spare  pilot  lamp.  Figs.  268,a,  6,  c  and 
d,  represent  various  forms  from  which  selection  may  be  made. 
All  are  adapted  for  the  same  purpose  and  differ  only  in  mechan- 
ical arrangement. 


ELECTRICITY 


381 


Service  Switch. — The  service  entrance  switch  may  be  selected 
from  the  three  styles  shown  in  Figs.  269,a,  b,  and  c. 


(a)  (b) 

FIG.  271. — Pilot  lights. 


(C)  (d) 

FIG.   272. — Wall  and  ceiling  sockets. 


Fig.  269,a  is  composed  of  a  30-ampere  porcelain  base  with  con- 
nections for  plug  fuses. 

Fig.  269,6  is  a  slate  base  with  connections  for  cartridge  fuses. 


382 


MECHANICS  OF  THE  HOUSEHOLD 


Fig.  269,  c  is  a  slate  base  with  connections  for  open-link  fuses 
Local  Switches. — Local  wall  switches  may  be  selected  from  the 
various  styles  shown  in  Figs.  270,a,  b,  c,  d  and  e. 

Fig.  270, a  is  the  two-button  flush  type  completely  enclosed  in  a 
box  of  non-breakable  insulating  material  with  brass  beveled 
cover  plate  finished  to  match  surrounding  hardware. 


FIG.  273. — Drop-light  attachments  and  lamp  bases. 

Fig.  270, b  is  a  two-button  flush  type  with  brass  beveled-edge 
cover  plate  finished  to  match  surrounding  hardware. 

Fig.  270,  c  is  of  the  removable-mechanism  type  with  brass  bev- 
eled-edge cover  plate  finished  to  match  surrounding  hardware. 

Fig.  270,d  is  the  single-button  flush  type  with  brass  beveled- 
edge  cover  plate  finished  to  match  surrounding  hardware. 

Fig.  270, e  is  the  rotary-flush  type  with  brass  beveled-edge 
cover  plate  finished  to  match  surrounding  hardware. 


ELECTRICITY  383 

Pilot  Lights. — Switches  controlling  cellar,  attic  and  porch 
lights  may  be  either  Fig.  270,a  or  6. 

Fig.  270,a  requires  for  its  installation  a  two-gang  outlet  box. 
The  ruby  bull's-eye  which  covers  the  lamp  is  practically  flush, 
extending  from  the  wall  no  further  than  the  buttons  of  the 
switch. 

Fig.  270,6  is  installed  in  a  single-gang  box.  The  lamp  ex- 
tends through  the  plate  and  is  protected  by  a  perforated  cage 
which  extends  about  an  inch  from  the  plate. 

Wall  and  Ceiling  Sockets. — One-light  ceiling  receptacles  may 
be  selected  from  the  types  shown  in  Figs.  272, a,  b,  c,  d  and  e. 

Fig.  272, a  is  of  a  type  to  fit  standard  3^-inch  or  4-inch 
,  outlet  boxes. 

Fig.  272,6  is  of  the  small  concealed-base  type. 

Fig.  272, c  is  of  the  large  concealed-base  type. 

Fig.  272,  d  is  of  the  insulated-base  type. 

Fig.  272, e  is  of  the  porcelain-base  type. 

Sockets  in  cellars  shall  be  made  entirely  of  porcelain.  Those 
in  bathrooms  shall  be  entirely  of  porcelain  and  of  the  pull  type. 

Drop  Lights. — Drop  lights  shall  consist  of  the  necessary 
length  of  reinforced  cord  supported  by  either  brass  or  porcelain 
bases.  Each  drop  cord  to  have  an  adjuster.  Figs.  273,a,  b,  c,  d,  e, 
/,  g,  illustrate  the  various  styles.  Fig.  273, h  is  a  shade  holder  to 
be  used  with  the  drop  lights. 


INDEX 


Acetylene,  gas  burner,  302 

gas  machine,  the  Colt,  300 

machines,  295 
generators,  types  of,  297 
stoves,  304 
Air  conditioning,  240 
cooling  plants,  244 
discharged  by  a  flue,  225 
eliminators,  35,  36 
properties  of,  table,  199 
tester,  the  Wolpeit,  233 
valves,  19 
Alcohol,  sad  irons,  289 

table  stoves,  293 
Annunciators,  346 
Anthracite,  graphitic,  186 
Atmospheric  humidity,  196 


B 


Backventing,  of  plumbing,  105 
Bathroom,  97 
Bathtubs,  98 

fixtures  for,  100 
Bibb,  compression  flange,  89 

flange,  89 

Fuller,  89 

hose,  89 

lever  handle,  90 

screw,  89 

self-closing,  90 

solder,  89 

wash-tray,  91 
Boiler,  at  end  of  season,  79 

cast-iron,  19,  20,  38 

cylindrical  form  of,  38 

house  heating,  19,  24 

rules  for  management  of,  77 

sheet-metal,  19 


Boiler,  steam,  rules  for  management 
of,  78 

the  house-heating  steam,  19 
Boyles'  law,  definition,  161,  272 
Briquettes,  189 
British  thermal  units,  4 

for  one  cent,  190 
B.t.u.,  2,  32,  182,  185 
Burglar  alarms,  344 
Buzzers,  344 


Candle,  foot,  313 

Hefner,  310 

power,  310 

horizontal,  310 
spherical,  311 
Cellar  drain,  84 

Cell,  Pilot,  storage  battery,  370 
Cesspools,  169 
Charcoal,  188 
Check-draft  damper,  24 
Chimney  flue,  the  right,  79 
Chimneys,  "smokey,"  80,  81 
Cisterns,  filters  for,  152,  153 

galvanized  iron  tanks  as,  152 

rain-water,  151 

wooden,  152 
Clinkers,  72,  73 
Close-nipples,  28 
Coal,  182 

anthracite  or  hard,  183,  193 

bituminous  or  soft,  184 

burning  soft,  75 

calorific  value  of  typical  Ameri- 
can, 192,  193 

cannel,  186 

coking,  184 

comparative  value  of,  189 

free  burning,  75 


385 


386 


INDEX 


Coal,  fusing-coking,  75 

grades  of  soft,  184 

pea  size,  76 

price  of,  190,  191 

semi-bituminous,  186,  193 
Cocks,  basin,  92 

bibb,  88 

corporation,  87 

curb,  87 

Fuller,  91 
bibb,  89 
repairs  for,  91 

pantry,  93 

sill,  93 

stop  and  drain,  88 

stop  and  waste,  87 
Code,  national  electric,  371 
Coke,  76,  188 

gas,  188 

Column,  the  water,  22 
Condensation,  water  of,  6,  10,   11, 

15,  35 

Conductors,  374 
Cord,  lamp,  363 

portable,  363 
Current,  alternating,  332 

direct,  332 


D 


Damper,  ash-pit,  59 

check-draft,  24,  67,  69,  70 

direct-draft,  59,  61,  67 

regulator,  59,  60 

combined  thermostat  and,  67 
for  hot-water  furnaces,  61,  62 
for  steam  boiler,  60,  78 
Design,  heating  plant,  44 
Devining  rod,  137 
Dew-point,  209 

to  determine  the,  212 
Dim-a-lite,  323 
Door  bells,  342 
Draft,  economy  of  good  furnace,  70 

hand,  regulation,  59 

induced,  69 
Drip-cock,  23 


Dry  cells,  354 


Electric  annunciators,  346 

batteries,  354 

battery  formation,  358 
testers,  360 

burglar  alarms,  344 

buzzers,  344 

conductors,  362 

door  bell,  342 

dry  cell,  355 

flat-iron,  326 

fuse  plugs,  334,  337 

generating  plants,  363 

heaters,  338 

heating  devices,  305 

lamp  cord,  362 

lamps,  Gem,  306 
incandescent,  306 

motors,  332 

panel,  336 

range,  340 

signals,  341 

stoves,  339 

table  pushes,  346 

toaster,  330 

Electrical  measurements,  units  of,  317 
Electricity,  305 
Eliminator,  air,  35,  36 
Evaporation  as  a  cooling  agent,  243 


Filaments,  carbon,  308 

incandescent  lamp,  306,  307 

tungsten,  307 
Fire-box,  19,  20,  54 
Firing,  first  day,  73 

in  moderate  weather,  74 

in  severe  weather,  74 

night,  72 
Fixtures,  bathroom,  105 

kitchen  and  laundry,  94 
Flat-iron,  electric,  326 
Flues,  furnace,  55 


INDEX 


387 


Flush  tanks,  110 

details  of  construction,  112,  113 
low  down,  111 
Foot-candle,  313 
Frost  prediction,  212 
Fuels,    comparative   value    of    coal 

to  other,  189 
danger  from  gaseous  and  liquid, 

294 

heating  values  of  domestic,  252 
moisture  in,  194 
Furnace,  cast-iron,  54 

firing,  general  rules  for,  70 

times  of  day  for,  72 
location  of,  54 
the  hot-air,  51,  52 

construction  of,  52 
Furnace-gas  leaks,  54 
Fuse  plugs,  334 


G 


Gage,  Bourdon  type  of,  23 

electrified  Bourdon  spring  pres- 
sure, 36 

glass,  22,  40,  161,  162 

steam,  22 

water,  22 
Gas,  acetylene,  machines,  295 

all-oil  water,  251 

blau,  251 

burner,  Bunsen,  275 
open-flame,  278 

coal,  250 

lamps,  mantle,  274,  276,  277 

lighters,  302 

measurements  of,  253 

meter  dials,  reading  of,  255,  256 

meters,  254 

prepayment,  256 

Pintsch,  251 

service  rules,  256,  257 

ranges,  258 

water,  251 

Gases,  heating  values  of,  252 
Gasoline,  250 

Beaume  test  of,  261 


Gasoline,  boulevard  lamp,  287 

central  generator  plants  for  use 

of,  282 
cold  process  system  of  lighting 

with,  264,  265 
gas  lamps,  286 
gravity  test  of,  262 
hollow-wire  system  of  lighting 

and  heating  with,  2691 
lamps,  inverted  mantle,  279 

portable,  280,  281 
lighting  and  heating  with,  259, 

264 

regulation  and  sale  of,  261 
sad  irons,  289 
stoves,  burners  for,  288 
Gate  valve,  94 
Globe  valve,  93 

angle,  94 
Grate  surface,  53 
Gravity  system,  low  pressure,  6,  15 


II 


Heaters,    combination    hot-air   and 

hot-water,  56 
direct  and  indirect,  28 
furnace  hot-water,  122 
instantaneous,  123 
tank,  121 
wash  boilers,  96 
Heating,  C.  A.  Dunham's  system  of 

vapor,  34,  35 
direct  indirect,  30 
hot-water,  26 
indirect  method  of,  29,  30 
low  pressure  system  of,  5,  6 
overhead    or    drop    system    of 

steam,  14 

system  of  hot  water,  44 
plants,  management  of,  70 
separate  return  system  of 

steam,  13 
single   pipe   system   of    steam, 

6,  12,  15 
steam,  26 
surface  of  furnaces,  56 


388 


INDEX 


Heating,  radiators,  26 

two  pipe  system  of  steam,  6,  10, 

11,  15 
Heat,  of  vaporization,  2 

specific,  37 
Hot-air  furnace,  61 
'     Hot-water  heaters,  38 
House  drain,  82 
Humidifying  apparatus,  215 

plants,  242 
Humidity,  absolute,  196 

atmospheric,  196 

control,  244 

of  the  air,  196 

relative,  197,  204 
Hydraulic  ram,  154 

double  acting,  157 

single  acting,  155 
Hydrometer,  storage  battery,  368 
Hygrodeik,  206 
Hygrometer,  204 

dial,  208 


Illumination,  313 
intensity  of,  314 
quantity  of,  314 

K 

Kerosene,  263 

legal  tests  for,  263 


Lamp,  base,  the  Edison,  311 
cord,  363 
labels,  312 

Lamps,  boulevard,  287 
carbon  filament,  311 
central-generator  gas,  286 
daylight,  electric,  324 
gas-filled  electric,  324 
incandescent  electric,  306 

mantle,  276 
inverted-mantle  gasoline,  279 


Lamps,  Mazda,  310 

miniature  electric,  320,  325 

portable,  gasoline,  280 

tantalum,  306 

tungsten-filament,  306 

turn-down  electric,  321 
Lights,  drop,  383 

flash,  326 

pilot,  383 
Lignite,  186 
Lumen,  313 

O 

Outlet  boxes,  373 
Overflow  pipe,  45 
Overheated  water,  47 


Peat,  187 
Pilot  light,  375 
Pipes,  covering,  33 

eliminator,  36 

flow,  57 

openings  stopped,  113 

overflow,  40,  41 

return,  6,  10,  57 

supply,  6,  10 
Plant,  hot-water  heating,  37 

steam  heating,  1,  5 
Plug  receptacles,  378 
Plumbers  friend,  113 
Plumbing,  81 

rough,  82 
Pneumatic  motor  valve,  237 

radiator  valve,  237 
Polluted  water,  134 
Pollution  of  wells,  134 
Pressure,  absolute,  4 

gage,  4 

tank,  162 

vapor,  35,  36 
Properties  of  steam,  3 
Psychrometer,  207 
Pump,  force,  the,  146 

lift,  the,  144 

tank,  146 


INDEX 


389 


Pumps,  144 
chain,  151 
deep  well,  150 
for  driven  wells,  150 
priming  of,  145 
well,  148 
wooden,  148 


Radiating  surface,  1,  21,  22,  27 
Radiators,  air  vent  on,  77 

connections,  10,  47 

corner,  28 

finishings,  31 

forms  of,  26 

hot-water,  28,  49 

rules  for  proportioning,  24,  25 

single  column,  2C 
pipe,  10,  15 

three  column,  28 

to  control,  79 

wall,  28 

water-filled,  15 
Range  boilers,  115 

blow-off  cock,  118 

double  heater  connections  for, 
119 

excessive  pressure  in,  117 

horizontal,  119 

location,  118 
Reflectors,  315 

choice  of,  316 

focusing,  316 

holoplane,  315 

intensive,  316 

Registers,  rules  for  proportioning,  55 
Regulator,  combined  thermostat  and 
damper,  67 

damper,  59,  60,  67 

draft,  24 

temperature,  59,  67 
Riser,  6,  10 

S 

Sad  irons,  alcohol,  292 
gasoline,  289 


Safety  valve,  24,  44,  47,  67 
Septic  tank,  170 

and  anaerobic  filter,  174 

automatic  siphon  for,  176 

concrete,  179 

limit  of  efficiency  of,  178 

Universal  Portland  Cement  Co., 
179 

with  sand-bed  filter,  171 
Sewage,  168 

disposal,  168 

purification,  168 
Sewer,  82,  85 

gas,  114 

Short  circuiting,  334 
Sitz  bath,  98 
Slicing  bar,  72 
Slugging,  15 
Soil  pipe,  84,  107 
Soot  pocket,  80 
Stand  pipe  eliminator,  36 
Steam  temperatures,  4 
Stop-cock,  46 
Stove,  acetylene,  292 

gasoline,  288 

putty,  54 
Surface,  grate,  53 

air-heating,  53 
Surging,  15 
Switch,  automatic  door,  378 

heater,  380 

local,  382 

service,  381 
System,  high-pressure  hot-water,  41 

low-pressure  gravity,  6 
hot-water,  38 

overhead  or  drop,  14 

separate  return,  13 

single  pipe,  8 

two  pipe,  10 


Table,  air  discharged  from  flues,  229 
required  for  ventilation,  220 
calorific     value     of     American 
coals,  192 


390 


INDEX 


Table,  dew-point,  210,  211 
frost  prediction,  214 
heating  values  of  coals,  93 
gases,  252 
wood,  187,  188 
hot-air  furnaces,  51 

registers,  51 
lumens  per  watt,  314 
prices  of  fuels,  191 
properties  of  air,  199 

steam,  3 

radiators,  sizes  of,  27 
record  of  evaporation  from  hot- 
air  furnace,  217 

relative  heating  values  of  do- 
mestic fuel,  252 
humidity,  202,  203 
sizes  of  hard  coal,  183 
heating  mains,  26 
hot-air  furnaces,  51 
soft  coal,  184 

thermal  units  for  one  cent,  190 
Table  pushes,  346 
Tank  heaters,  121 

expansion,  38,  40,  41,  45,  46,  47 
Telephones,  intercommuni  eating, 

340 

Temperature  regulation,  59 
hand,  59 
pneumatic,  234 
Thermostats,  62,  67 
controllers,  62,  63 
electric,  62 
motor,  64 
National   Regulator   Co.,    235, 

236 

pneumatic,  62 
time  attachment,  63 
Transformers,  bell-ringing,  347 

lamp,  316 
Traps,  Bower,  103 
clean  sweep,  103 
drum,  103,  105 

for  bathroom  fixture,  102,  103 
inside,  83 

non-siphoning,  105 
outside,  83 


Traps,  sewer  for  house  drains,  82 

siphoning,  106 

S,  103,  104 
Try-cocks,  22,  23 
Tungsten,  307 


D 


Union  joint,  18 


Vacuum,  5 
Valve,  air,  79 

angle,  18 

check,  42,  43 

definition  of,  88,  93 

disc,  19 

gjobe,  93 

hot-water  radiator,  49 

Ohio  hot-water,  49 

on  cellar  mains,  78 

safety,  24,  44,  47 

steam  radiator,  18 

stem,  19 
Valves,  definition  of,  93 

globe,  93 

Vaporization,  heat  of,  2 
Ventilation,  219 

apparatus,  239 

by  direct  method  of  heating,  31 

by  indirect  method  of  heating, 
31 

cost  of,  230 

DeChaumont  standard  of,  219 

mechanical,  237 

of  dwellings,  222,  223,  224 

Plenum  method  of,  239 

quantity  of  air  required  for,  220 
Vents,  air,  16,  45,  48,  49 

automatic  air,  16 
hot-water  air,  50 

Monash  No.  16  air,  16  . 

pipe,  83 

radiator,  16 

sewer,  85 

the  Allen  float,  16 


INDEX 


391 


Voltage  variation,  effect  of,  321 
W 

Wash  stands  and  lavatories,  101 
Waste  stack,  84,  85 
Water,  ammonia  in,  130 
analyses,  126 
artesian,  128 
back,  115 
chlorine  in,  133 
closets,  108 
siphon-jet,  108 
washdown,  109 
washout,  108 
frost,  115 
hammer,  9,  15 
hardness  in,  131 
iron  in,  131 
lift,  165 
medical,  128 
of  condensation,  11 
organic  matter  in,  130 
overheated,  121 
Pokegama,  127 
polluted,  133 
river,  127 
seal,  83 

softening    with    hydrated    sili- 
cates, 132 
supply,  87,  125 
electric  power,  164 
plants,  domestic,  158 
gravity,  158 


Water,  power,  163 

pressure  tank  system  of,  160 
wind  power,  164 
table,  137 
Wattmeter,  periodic  tests  of,  354 

readings,  352 

recording,  350 

state  regulation  of,  353 

to  read  the,  350 
Well,  the  ideal,  140 
Wells,  artesian,  140 

bored,  141 

breathing,  143 

cleaning  of,  142 

concrete  coverings  for,  140 

construction  of,  138 

curbing  of,  136,  140 

cylinders  for  tubular,  151 

driven,  141 

dug,  139 

flowing,  138 

freezing,  144 

gases  in,  142 

open,  139 

peculiarities  of,  143 

safe  distance  in  the  location  of, 
135 

selection  of  the  type  of,  138 

surface  pollution  of,  135 
Wiped  joints,  107 
Wire  annunciator,  353 
Wiring,  electric  light,  372 
Wood,  187 

heating  value  of,  187 


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1990 
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